signature extraction failed

[A-Mani]

I am using latest version on youtube-dl on Ubuntu latest
The problem happens with some video files only (for example v=FirX7LLpE08 has no problem with same command )

youtube-dl -f 43 --prefer-free-formats https://www.youtube.com/watch?v=qNp6UB6JhFE

[youtube] qNp6UB6JhFE: Downloading webpage
[youtube] qNp6UB6JhFE: Downloading video info webpage
[youtube] qNp6UB6JhFE: Extracting video information
ERROR: Signature extraction failed: Traceback (most recent call last):
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 817, in _decrypt_signature
video_id, player_url, s
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 709, in _extract_signature_function
raise ExtractorError('Cannot identify player %r' % player_url)
ExtractorError: Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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"Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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 VERSION

youtube-dl -f 43 --prefer-free-formats --verbose https://www.youtube.com/watch?v=qNp6UB6JhFE
[debug] System config: []
[debug] User config: []
[debug] Command-line args: [u'-f', u'43', u'--prefer-free-formats', u'--verbose', u'https://www.youtube.com/watch?v=qNp6UB6JhFE']
[debug] Encodings: locale UTF-8, fs UTF-8, out UTF-8, pref UTF-8
[debug] youtube-dl version 2015.10.24
[debug] Python version 2.7.10 - Linux-4.2.0-30-lowlatency-x86_64-with-Ubuntu-15.10-wily
[debug] exe versions: ffmpeg 2.7.6-0ubuntu0.15.10.1, ffprobe 2.7.6-0ubuntu0.15.10.1, rtmpdump 2.4
[debug] Proxy map: {}
[youtube] qNp6UB6JhFE: Downloading webpage
[youtube] qNp6UB6JhFE: Downloading video info webpage
[youtube] qNp6UB6JhFE: Extracting video information
WARNING: unable to extract html5 player; 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.
[youtube] {22} signature length 41.45, html5 player None
ERROR: Signature extraction failed: Traceback (most recent call last):
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 817, in _decrypt_signature
video_id, player_url, s
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 709, in _extract_signature_function
raise ExtractorError('Cannot identify player %r' % player_url)
ExtractorError: Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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"Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 817, in _decrypt_signature
video_id, player_url, s
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 709, in _extract_signature_function
raise ExtractorError('Cannot identify player %r' % player_url)
ExtractorError: Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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/bin/youtube-dl/youtube_dl/YoutubeDL.py", line 661, in extract_info
ie_result = ie.extract(url)
File "/usr/bin/youtube-dl/youtube_dl/extractor/common.py", line 291, in extract
return self._real_extract(url)
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 1345, in _real_extract
encrypted_sig, video_id, player_url, age_gate)
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 827, in _decrypt_signature
'Signature extraction failed: ' + tb, cause=e)
ExtractorError: Signature extraction failed: Traceback (most recent call last):
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 817, in _decrypt_signature
video_id, player_url, s
File "/usr/bin/youtube-dl/youtube_dl/extractor/youtube.py", line 709, in _extract_signature_function
raise ExtractorError('Cannot identify player %r' % player_url)
ExtractorError: Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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"Cannot identify player u'https://s.ytimg.com/yts/jsbin/player-en_US-vfl6PWeOD/base.js'; 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.

[phihag]

You are not using the latest version of youtube-dl; that would be 2016.03.06. Either request a current version from Ubuntu or see our FAQ on how to install a current version by hand.

[A-Mani]

Thanks.
I must have missed the path with "sudo youtube-dl --update"