Unsupported JS expression '['

[sj-dan]

Checklist

• I'm reporting a broken site support issue
• I've verified that I'm running youtube-dl version 2020.06.16.1
• I've checked that all provided URLs are alive and playable in a browser
• I've checked that all URLs and arguments with special characters are properly quoted or escaped
• I've searched the bugtracker for similar bug reports including closed ones
• I've read bugs section in FAQ

Verbose log

C:\Users\dan>youtube-dl https://www.youtube.com/watch?v=moZtoMP7HAA -v
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['https://www.youtube.com/watch?v=moZtoMP7HAA', '-v']
[debug] Encodings: locale cp1252, fs utf-8, out utf-8, pref cp1252
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 3.8.3 (CPython) - Windows-10-10.0.18362-SP0
[debug] exe versions: ffmpeg git-2020-06-17-0b3bd00, ffprobe git-2020-06-17-0b3bd00
[debug] Proxy map: {}
[youtube] moZtoMP7HAA: Downloading webpage
[youtube] {18} signature length 108, html5 player f82a8c37
[youtube] moZtoMP7HAA: Downloading player https://www.youtube.com/s/player/f82a8c37/player_ias.vflset/en_US/base.js
ERROR: Signature extraction failed: Traceback (most recent call last):
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.")); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\YoutubeDL.py", line 797, in extract_info
    ie_result = ie.extract(url)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 2106, in _real_extract
    signature = self._decrypt_signature(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1435, in _decrypt_signature
    raise ExtractorError(
youtube_dl.utils.ExtractorError: Signature extraction failed: Traceback (most recent call last):
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "c:\users\dan\appdata\local\programs\python\python38-32\lib\site-packages\youtube_dl\jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.")); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

Description

When I try to download this video: https://www.youtube.com/watch?v=moZtoMP7HAA, it gives me the error: "Unsupported JS expression '['", and it happens with any video that has special characters in the title, such as https://www.youtube.com/watch?v=yzC4hFK5P3g. Not sure what to do.

[splattadat]

I'm seeing the same with... https://www.youtube.com/watch?v=08y9BUJS4JM and no special characters in the title... Luciano performing with the Royal Philharmonic Orchestra - Full Concert

Short log:

> youtube-dl.exe -U
youtube-dl is up-to-date (2020.06.16.1)

> youtube-dl.exe https://www.youtube.com/watch?v=08y9BUJS4JM
[youtube] 08y9BUJS4JM: Downloading webpage
[youtube] 08y9BUJS4JM: Downloading js player f82a8c37
ERROR: Signature extraction failed: Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1426, in _decrypt_signature
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 258, in resf
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 92, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 189, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 211, in interpret_expression
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.",)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

Verbose log...

[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['--verbose', 'https://www.youtube.com/watch?v=08y9BUJS4JM']
[debug] Encodings: locale cp1252, fs mbcs, out cp65001, pref cp1252
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 3.4.4 (CPython) - Windows-10-10.0.18362
[debug] exe versions: ffmpeg N-94664-g0821bc4eee, ffprobe N-94664-g0821bc4eee
[debug] Proxy map: {}
[youtube] 08y9BUJS4JM: Downloading webpage
[youtube] {18} signature length 108, html5 player f82a8c37
[youtube] 08y9BUJS4JM: Downloading player https://www.youtube.com/s/player/f82a8c37/player_ias.vflset/en_US/base.js
ERROR: Signature extraction failed: Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1426, in _decrypt_signature
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 258, in resf
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 92, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 189, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 211, in interpret_expression
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.",)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1426, in _decrypt_signature
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 258, in resf
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 92, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 189, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 211, in interpret_expression
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1426, in _decrypt_signature
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 258, in resf
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 92, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 189, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 211, in interpret_expression
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\YoutubeDL.py", line 797, in extract_info
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\common.py", line 530, in extract
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 2107, in _real_extract
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1436, in _decrypt_signature
youtube_dl.utils.ExtractorError: Signature extraction failed: Traceback (most recent call last):
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1426, in _decrypt_signature
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1338, in _extract_signature_function
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\extractor\youtube.py", line 1402, in <lambda>
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 258, in resf
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 92, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 189, in interpret_expression
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 56, in interpret_statement
  File "C:\Users\dst\AppData\Roaming\Build archive\youtube-dl\ytdl-org\tmpspbsbtmq\build\youtube_dl\jsinterp.py", line 211, in interpret_expression
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.",)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

[SHGuy1]

Same error with a regular video here, with Video title Cloud of Forgetting:

❯ youtube-dl -x -f bestaudio --no-playlist -o "%(title)s.%(ext)s" --verbose https://youtu.be/hyKDdr31Hu4
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: ['-x', '-f', 'bestaudio', '--no-playlist', '-o', '%(title)s.%(ext)s', '--verbose', 'https://youtu.be/hyKDdr31Hu4']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 3.8.4 (CPython) - Linux-5.7.10-zen1-1-zen-x86_64-with-glibc2.2.5
[debug] exe versions: ffmpeg 4.3.1, ffprobe 4.3.1
[debug] Proxy map: {}
[youtube] hyKDdr31Hu4: Downloading webpage
[youtube] Downloading just video hyKDdr31Hu4 because of --no-playlist
[youtube] {18} signature length 108, html5 player f82a8c37
[youtube] hyKDdr31Hu4: Downloading player https://www.youtube.com/s/player/f82a8c37/player_ias.vflset/en_US/base.js
ERROR: Signature extraction failed: Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.")); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/youtube_dl/YoutubeDL.py", line 797, in extract_info
    ie_result = ie.extract(url)
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 2106, in _real_extract
    signature = self._decrypt_signature(
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1435, in _decrypt_signature
    raise ExtractorError(
youtube_dl.utils.ExtractorError: Signature extraction failed: Traceback (most recent call last):
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/usr/lib/python3.8/site-packages/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/usr/lib/python3.8/site-packages/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.")); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; see  https://yt-dl.org/update  on how to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

[cepacolmax]

Same issue, different content link.

$ youtube-dl -U
youtube-dl is up-to-date (2020.06.16.1)

Here's the --verbose:

$ youtube-dl --verbose https://www.youtube.com/watch?v=2ovZgUU9kgM
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u'--verbose', u'https://www.youtube.com/watch?v=2ovZgUU9kgM']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 2.7.17 (CPython) - Linux-4.4.0-18362-Microsoft-x86_64-with-Ubuntu-18.04-bionic
[debug] exe versions: none
[debug] Proxy map: {}
[youtube] 2ovZgUU9kgM: Downloading webpage
[youtube] {18} signature length 108, html5 player f82a8c37
[youtube] 2ovZgUU9kgM: Downloading player https://www.youtube.com/s/player/f82a8c37/player_ias.vflset/en_US/base.js
ERROR: Signature extraction failed: Traceback (most recent call last):
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1426, in _decrypt_signature
video_id, player_url, s
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
cache_res = res(test_string)
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in
return lambda s: initial_function([s])
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
res, abort = self.interpret_statement(stmt, local_vars)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
v = self.interpret_expression(expr, local_vars, allow_recursion)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 92, in interpret_expression
m.group('expr'), local_vars, allow_recursion - 1)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 189, in interpret_expression
m.group('x'), local_vars, allow_recursion - 1)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
v = self.interpret_expression(expr, local_vars, allow_recursion)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
raise ExtractorError('Unsupported JS expression %r' % expr)
ExtractorError: Unsupported JS expression u'['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
(caused by ExtractorError(u"Unsupported JS expression u'['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.",)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1426, in _decrypt_signature
video_id, player_url, s
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
cache_res = res(test_string)
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in
return lambda s: initial_function([s])
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
res, abort = self.interpret_statement(stmt, local_vars)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
v = self.interpret_expression(expr, local_vars, allow_recursion)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 92, in interpret_expression
m.group('expr'), local_vars, allow_recursion - 1)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 189, in interpret_expression
m.group('x'), local_vars, allow_recursion - 1)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
v = self.interpret_expression(expr, local_vars, allow_recursion)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
raise ExtractorError('Unsupported JS expression %r' % expr)
ExtractorError: Unsupported JS expression u'['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
File "/usr/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 797, in extract_info
ie_result = ie.extract(url)
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 530, in extract
ie_result = self._real_extract(url)
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 2107, in _real_extract
encrypted_sig, video_id, player_url, age_gate)
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1436, in _decrypt_signature
'Signature extraction failed: ' + tb, cause=e)
ExtractorError: Signature extraction failed: Traceback (most recent call last):
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1426, in _decrypt_signature
video_id, player_url, s
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
cache_res = res(test_string)
File "/usr/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in
return lambda s: initial_function([s])
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
res, abort = self.interpret_statement(stmt, local_vars)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
v = self.interpret_expression(expr, local_vars, allow_recursion)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 92, in interpret_expression
m.group('expr'), local_vars, allow_recursion - 1)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 189, in interpret_expression
m.group('x'), local_vars, allow_recursion - 1)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
v = self.interpret_expression(expr, local_vars, allow_recursion)
File "/usr/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
raise ExtractorError('Unsupported JS expression %r' % expr)
ExtractorError: Unsupported JS expression u'['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
(caused by ExtractorError(u"Unsupported JS expression u'['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.",)); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type youtube-dl -U to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

[klausness]

Same thing:

$ youtube-dl --verbose "https://www.youtube.com/watch?v=r4-uq8cTF7o"
[debug] System config: []
[debug] User config: ['-o', '/me/%(title)s-%(id)s.%(ext)s', '--add-metadata', '-f', 'bestvideo[ext=mp4]+bestaudio[ext=m4a]/best[ext=mp4]/best', '--prefer-ffmpeg']
[debug] Custom config: []
[debug] Command-line args: ['--verbose', 'https://www.youtube.com/watch?v=r4-uq8cTF7o']
[debug] Encodings: locale UTF-8, fs utf-8, out utf-8, pref UTF-8
[debug] youtube-dl version 2020.06.16.1
[debug] Python version 3.8.5 (CPython) - macOS-10.14.6-x86_64-i386-64bit
[debug] exe versions: avconv 12, avprobe 12, ffmpeg 4.2.4, ffprobe 4.2.4, rtmpdump 2.4
[debug] Proxy map: {}
[youtube] r4-uq8cTF7o: Downloading webpage
[youtube] {18} signature length 108, html5 player f82a8c37
[youtube] r4-uq8cTF7o: Downloading player https://www.youtube.com/s/player/f82a8c37/player_ias.vflset/en_US/base.js
ERROR: Signature extraction failed: Traceback (most recent call last):
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.")); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
Traceback (most recent call last):
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/opt/local/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 797, in extract_info
    ie_result = ie.extract(url)
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/common.py", line 530, in extract
    ie_result = self._real_extract(url)
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 2106, in _real_extract
    signature = self._decrypt_signature(
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1435, in _decrypt_signature
    raise ExtractorError(
youtube_dl.utils.ExtractorError: Signature extraction failed: Traceback (most recent call last):
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1425, in _decrypt_signature
    func = self._extract_signature_function(
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1338, in _extract_signature_function
    cache_res = res(test_string)
  File "/opt/local/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1402, in <lambda>
    return lambda s: initial_function([s])
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 258, in resf
    res, abort = self.interpret_statement(stmt, local_vars)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 91, in interpret_expression
    right_val = self.interpret_expression(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 188, in interpret_expression
    x, abort = self.interpret_statement(
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 56, in interpret_statement
    v = self.interpret_expression(expr, local_vars, allow_recursion)
  File "/opt/local/bin/youtube-dl/youtube_dl/jsinterp.py", line 211, in interpret_expression
    raise ExtractorError('Unsupported JS expression %r' % expr)
youtube_dl.utils.ExtractorError: Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.
 (caused by ExtractorError("Unsupported JS expression '['; please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.")); please report this issue on https://yt-dl.org/bug . Make sure you are using the latest version; type  youtube-dl -U  to update. Be sure to call youtube-dl with the --verbose flag and include its complete output.

[PlasmaPower]

I think we have enough backtraces 😛 this is happening on all videos for everyone as far as I can tell.

[MattLomas]

it has happened very recently given my last successful download was 20.57 (BST, London)

[qwertz19281]

it seems to affect videos that require to extract js player (f82a8c37)

[Friz64]

Isn't this a duplicate of #26135?

[xdenyer]

I think everything opened in the last hour or so is the same underlying issue.

[ethanccss]

Same thing, only downloaded 3 out of 35 links. Major bug.

[sj-dan]

Jeez, so I'm one of many people having this issue.

[splattadat]

Yeah duplicate of ...
#26137
#26135
#26134

[sj-dan]

Wow, has this not come to the creator's attention yet, or has the update/bug fix just not been released? If it hasn't come to their attention, I'm actually surprised...

[newperson1746]

This was pretty major. I have youtube-dl from pip3. When are updates pushed to the pip repo?

[xdenyer]

The issue only appears to have started today, so all we can really do as end users now is leave contributors to look at it when they get chance.