Youtube fails to authenticate consistently

[HPP8140]

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Make sure you are using the latest version: run youtube-dl --version and ensure your version is 2017.05.01. If it's not read this FAQ entry and update. Issues with outdated version will be rejected.

• I've verified and I assure that I'm running youtube-dl 2017.05.01

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If the purpose of this issue is a bug report, site support request or you are not completely sure provide the full verbose output as follows:

Add -v flag to your command line you run youtube-dl with, copy the whole output and insert it here. It should look similar to one below (replace it with your log inserted between triple ```):

**Failed:**
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u':ytwatchlater', u'-u', u'PRIVATE', u'-p', u'PRIVATE', u'-v', u'-s', u'-j', u'--flat-playlist']
[debug] Encodings: locale ANSI_X3.4-1968, fs ANSI_X3.4-1968, out None, pref ANSI_X3.4-1968
[debug] youtube-dl version 2017.05.01
[debug] Python version 2.7.9 - Linux-3.14.0-kirkwood-tld-1-armv5tel-with-debian-8.5
[debug] exe versions: avconv 11.6-6, avprobe 11.6-6, ffmpeg 0.8.20-6
[debug] Proxy map: {}
WARNING: unable to log in: bad username or password
ERROR: This playlist does not exist.
Traceback (most recent call last):
  File "/usr/lib/python2.7/youtube_dl/YoutubeDL.py", line 760, in extract_info
    ie_result = ie.extract(url)
  File "/usr/lib/python2.7/youtube_dl/extractor/common.py", line 429, in extract
    ie_result = self._real_extract(url)
  File "/usr/lib/python2.7/youtube_dl/extractor/youtube.py", line 2504, in _real_extract
    _, playlist = self._extract_playlist('WL')
  File "/usr/lib/python2.7/youtube_dl/extractor/youtube.py", line 2046, in _extract_playlist
    raise ExtractorError(message, expected=True)
ExtractorError: This playlist does not exist.

**Worked a couple minutes later (after a few tries):**
[debug] System config: []
[debug] User config: []
[debug] Custom config: []
[debug] Command-line args: [u':ytwatchlater', u'-u', u'PRIVATE', u'-p', u'PRIVATE', u'-v', u'-s', u'-j', u'--flat-playlist']
[debug] Encodings: locale ANSI_X3.4-1968, fs ANSI_X3.4-1968, out None, pref ANSI_X3.4-1968
[debug] youtube-dl version 2017.05.01
[debug] Python version 2.7.9 - Linux-3.14.0-kirkwood-tld-1-armv5tel-with-debian-8.5
[debug] exe versions: avconv 11.6-6, avprobe 11.6-6, ffmpeg 0.8.20-6
[debug] Proxy map: {}
...
<end of log>

Description of your issue, suggested solution and other information

Youtube fails to authenticate consistently...works 50/50. I think it is related to new sign-in page.
https://support.google.com/accounts/answer/7338427?visit_id=0-636291563247234608-2983872999&p=signin_newlook&rd=1.

[dstftw]

Duplicate of #12927.