YouTube said: Unable to extract video data

[yufeiluo]

My youtube-dl is the latest version:

    youtube-dl --version
    2020.07.28

Try to download video on youtube.

    url="https://www.youtube.com/watch?v=bpAi70WWBlw"
    youtube-dl -v   $url
    [debug] System config: []
    [debug] User config: []
    [debug] Custom config: []
    [debug] Command-line args: ['-v', 'https://www.youtube.com/watch?v=bpAi70WWBlw']
    [debug] Encodings: locale UTF-8, fs utf-8, out UTF-8, pref UTF-8
    [debug] youtube-dl version 2020.07.28
    [debug] Python version 3.5.3 (CPython) - Linux-4.9.0-12-amd64-x86_64-with-debian-9.12
    [debug] exe versions: ffmpeg 3.2.14-1, ffprobe 3.2.14-1
    [debug] Proxy map: {}
    [youtube] bpAi70WWBlw: Downloading webpage
    ERROR: bpAi70WWBlw: YouTube said: Unable to extract video data
    Traceback (most recent call last):
      File "/usr/local/lib/python3.5/dist-packages/youtube_dl/YoutubeDL.py", line 797, in extract_info
        ie_result = ie.extract(url)
      File "/usr/local/lib/python3.5/dist-packages/youtube_dl/extractor/common.py", line 530, in extract
        ie_result = self._real_extract(url)
      File "/usr/local/lib/python3.5/dist-packages/youtube_dl/extractor/youtube.py", line 1893, in _real_extract
        'YouTube said: %s' % unavailable_message, expected=True, video_id=video_id)
    youtube_dl.utils.ExtractorError: bpAi70WWBlw: YouTube said: Unable to extract video data

How to fix it?