ERROR: Signature extraction failed | Unable to extract Initial JS player signature function name

[gui113]

This error appeared with 4/16 videos that I tried to download. I can't found anything in common between the 4 videos. The videos are:

• https://www.youtube.com/watch?v=Sk8LSqSDjxc
• https://www.youtube.com/watch?v=GK5S8sT2574
• https://www.youtube.com/watch?v=L4EfsAkDcRI
• https://www.youtube.com/watch?v=5-xlDxfsLzA

Here is the log:

$ youtube-dl --verbose --max-quality --audio-quality --extract-audio https://www.youtube.com/watch?v=5-xlDxfsLzA
[debug] System config: []
[debug] User config: []
[debug] Command-line args: ['--verbose', '--max-quality', '--audio-quality', '--extract-audio', 'https://www.youtube.com/watch?v=5-xlDxfsLzA']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2014.08.05
[debug] Python version 2.7.8 - Linux-3.16.0-36-generic-x86_64-with-Ubuntu-14.10-utopic
[debug] Proxy map: {}
[youtube] Setting language
[youtube] 5-xlDxfsLzA: Downloading webpage
[youtube] 5-xlDxfsLzA: Downloading video info webpage
[youtube] 5-xlDxfsLzA: Extracting video information
[youtube] 5-xlDxfsLzA: Encrypted signatures detected.
[youtube] {22} signature length 43.43, html5 player en_US-vflheTb7D
[youtube] 5-xlDxfsLzA: Downloading js player vflheTb7D

ERROR: Signature extraction failed: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 479, in _decrypt_signature
    video_id, player_url, s
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 383, in _extract_signature_function
    res = self._parse_sig_js(code)
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 454, in _parse_sig_js
    u'Initial JS player signature function name')
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 391, in _search_regex
    raise RegexNotFoundError(u'Unable to extract %s' % _name)
RegexNotFoundError: Unable to extract Initial JS player signature function name; please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl with the --verbose flag and include its complete output. Make sure you are using the latest version; type  youtube-dl -U  to update.
; please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl with the --verbose flag and include its complete output. Make sure you are using the latest version; type  youtube-dl -U  to update.
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 479, in _decrypt_signature
    video_id, player_url, s
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 383, in _extract_signature_function
    res = self._parse_sig_js(code)
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 454, in _parse_sig_js
    u'Initial JS player signature function name')
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 391, in _search_regex
    raise RegexNotFoundError(u'Unable to extract %s' % _name)
RegexNotFoundError: Unable to extract Initial JS player signature function name; please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl with the --verbose flag and include its complete output. Make sure you are using the latest version; type  youtube-dl -U  to update.
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/youtube_dl/YoutubeDL.py", line 516, in extract_info
    ie_result = ie.extract(url)
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 170, in extract
    return self._real_extract(url)
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 860, in _real_extract
    encrypted_sig, video_id, player_url, age_gate)
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 489, in _decrypt_signature
    u'Signature extraction failed: ' + tb, cause=e)
ExtractorError: Signature extraction failed: Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 479, in _decrypt_signature
    video_id, player_url, s
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 383, in _extract_signature_function
    res = self._parse_sig_js(code)
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/youtube.py", line 454, in _parse_sig_js
    u'Initial JS player signature function name')
  File "/usr/lib/python2.7/dist-packages/youtube_dl/extractor/common.py", line 391, in _search_regex
    raise RegexNotFoundError(u'Unable to extract %s' % _name)

RegexNotFoundError: Unable to extract Initial JS player signature function name; please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl with the --verbose flag and include its complete output. Make sure you are using the latest version; type  youtube-dl -U  to update.
; please report this issue on https://yt-dl.org/bug . Be sure to call youtube-dl with the --verbose flag and include its complete output. Make sure you are using the latest version; type  youtube-dl -U  to update.

Bye!

[dstftw]

You are using an outdated version of youtube-dl. Read our FAQ if you have trouble updating.

[Wikinaut]

@dstftw This problem persists even after a git pull. I thought this would be sufficient. Pls. can you check?

[Wikinaut]

Problem solved after "youtube-dl -U".