ajax request returned an error with a status code of 0.
there is a file, which is passed to the background for processing, and the result is returned to execute other methods.
but background processing is slow, about 30s if slow.
then returns an error with a status code of 0.
later, when the file is smaller, it will be normal.
preliminary consideration may be that the ajax connection time is too long and an error has been reported.
ask if you have ever encountered this kind of situation and what is the solution.