processingFailure error (400) while retrieving CommentThreads list

Question

I a trying to retrieve all the comments of a video via Python iteration/paging. I am logged correctly with a developer key

import googleapiclient.discovery as gg
import googleapiclient.errors as gge

yt = gg.build(api_service_name= 'youtube', api_version= 'v3', developerKey = M_KEY)
comments= []
page= ''

while True:
        request = yt.commentThreads().list(
            part= "snippet,replies",
            order= "relevance",
            maxResults= 100,
            pageToken= page,
            textFormat= "plainText",
            videoId= video['id']
            # video is a static dictionary i've saved outside the script
        )

        try:
            response = request.execute()
            page= response['nextPageToken']
            comments.extend(response['items'])
            print('Comments extended')
        except KeyError:
            # there are no more pages
            print('Iteration ended')
            break
        except gge.HttpError as error:
            print('HTTP error:', error.__dict__['resp']['status'])

What i'm expecting it to do is iterate the pages of comments until the response['nextPageToken'] throws a KeyError, meaning that there are no more pages of comments. Instead, what happens is that the execution goes flawlessly for a dozen of iteration (at best) then it starts to throw said processingFailure error which content looks like this:

{
  "error": {
    "errors": [
      {
        "domain": "youtube.commentThread",
        "reason": "processingFailure",
        "message": "The API server failed to successfully process the request. While this can be a transient error, it usually indicates that the requests input is invalid. Check the structure of the <code>commentThread</code> resource in the request body to ensure that it is valid.",
        "locationType": "other",
        "location": "body"
      }
    ],
    "code": 400,
    "message": "The API server failed to successfully process the request. While this can be a transient error, it usually indicates that the requests input is invalid. Check the structure of the <code>commentThread</code> resource in the request body to ensure that it is valid."
  }
}

I have tried to log both the page and the videoId to ensure nothing went wrong with them but they're both valid. I've also tried to time.sleep() for up to 15 minutes when that error occurs but nothing changes.
This is the request in json format at the time of the error, catched using request.to_json(), thanks to @stvar for suggesting it:

{
  "uri": "https://www.googleapis.com/youtube/v3/commentThreads",
  "method": "POST",
  "body": "part=snippet%2Creplies&order=relevance&maxResults=100&pageToken=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&textFormat=plainText&videoId=CJ_GCPaKywg&key=m_developer_key&alt=json",
  "headers": {
    "accept": "application/json",
    "accept-encoding": "gzip, deflate",
    "user-agent": "google-api-python-client/1.7.9 (gzip)",
    "content-length": "5730",
    "x-http-method-override": "GET",
    "content-type": "application/x-www-form-urlencoded"
  },
  "methodId": "youtube.commentThreads.list",
  "resumable": null,
  "response_callbacks": [],
  "_in_error_state": false,
  "body_size": 0,
  "resumable_uri": null,
  "resumable_progress": 0
}

NOTE: I need to have order= "relevance" in my request because I primarly need the most voted comments.

An answer is nowhere to be found, I hope you can help me

Answer 1

Issue is, we can't really retrieve all the comments of every video.

https://issuetracker.google.com/issues/134912604
We currently don't support paging through the whole stream. So there's no way to retrieve all the 1000+ commentThreads that you have for that video