pytubefix.exceptions.RegexMatchError: get_initial_function_name: could not find match for multiple in https://youtube.com/s/player/377ca75b/player_ias.vflset/en_US/base.js

[abdwap]

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🐞 Bug Description

pytubefix.exceptions.RegexMatchError: get_initial_function_name: could not find match for multiple in https://youtube.com/s/player/377ca75b/player_ias.vflset/en_US/base.js

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# 3.9

[marader1984]

https://youtube.com/s/player/2b83d2e0/player_ias.vflset/en_US/base.js also

[darcyMaz]

I've got the same problem! For me it was caused by something very specific and I suspect this does not solve it for everyone.

I had this in my code to try to get around age verification.

    playlist = Playlist(link), 
        use_oauth=True,
        allow_oauth_cache=True)

By getting rid of it the problem went away.

    playlist = Playlist(link)

I suspect this solution won't fix it for you, but I hope it does!

[NannoSilver]

I am also getting such error for two different players:

get_initial_function_name: could not find match for multiple in https://youtube.com/s/player/2b83d2e0/player_ias.vflset/en_US/base.js

get_initial_function_name: could not find match for multiple in https://youtube.com/s/player/377ca75b/player_ias.vflset/en_US/base.js

[felipeucelli]

The latest player update has made obfuscation a real mess. The current jsinterp.py is unable to interpret the current functions. I believe pytubefix will have to find another way to interpret the signature functions.

[NannoSilver]

The latest player update has made obfuscation a real mess. The current jsinterp.py is unable to interpret the current functions. I believe pytubefix will have to find another way to interpret the signature functions.

Now the players use a WebAssembly HMAC/sha256-based function for signature handling.
In my tests seems it is possible to fix the get_initial_function_name() function, but not the get_throttling_function_name().

YT-DLP is working normally and, to fix the issue on Pytubefix, ChatGPT suggested:

You’d need to port yt-dlp’s throttling logic into pytubefix:

Their jsinterp.py knows about new JS constructs.

Their extractor/youtube.py handles wasm-based throttling differently (not through regex).

They sometimes hardcode fallbacks for known function patterns.

That’s non-trivial — it means merging quite a bit of yt-dlp’s logic.

[NannoSilver]

For who is not aware, while the WEB client is affected, the default client still is working, that is, if you replace this yt = YouTube(url, client='WEB') by this yt = YouTube(url) it works if there are no issues with your IP (if your IP not blocked by Youtube).

[felipeucelli]

I managed to fix the interpretation of the sig parameter.

The problem really seems to be nsig, it builds the array of objects and passes it to another function that does the transformation by calling several functions and the nsig function itself recursively.

I may be wrong but a while back I noticed yt-dlp working on an alternative to solve this problem yt-dlp/yt-dlp#14157

[felipeucelli]

I have a working implementation with nodejs (since it is needed for generating the poToken). It would be something like bot_guard.py, extracting the function name and letting nodejs do the magic, but I don't know if that would be a good idea.

[NannoSilver]

I have a working implementation with nodejs (since it is needed for generating the poToken). It would be something like bot_guard.py, extracting the function name and letting nodejs do the magic, but I don't know if that would be a good idea.

Do you have it available at some repository, where is possible to get a copy for testing?

[felipeucelli]

I was thinking of something like this (and I know it's ugly), but it still needs to be tested.

[NannoSilver]

I was thinking of something like this (and I know it's ugly), but it still needs to be tested.

Seems jsinterp.py is reaching the end of its service life.
I am not sure if my idea is valid, but... How about attaching node to pytubefix by using a library such as nodejs-wheel as a replacement for jsinterp.py? This will also be useful to pair with bot_guard.py and avoid the need to have node in a separate installation.

[felipeucelli]

The idea behind pytube was to build a library free of third-party dependencies, but YouTube's current situation doesn't leave many alternatives. If @JuanBindez agrees, we can implement it, and if we can fix jsinterp.py in the future, we can use it again.