OK API, what's the problem with uploading photos?

Question

API

Good afternoon!
The application uploads photos OK, everything according to the API documentation. I will not post the code, because it is 100% working - it has been working for more than a year for a large number of users.
The problem is that some requests receive a response of this format:
Err: {"error_code":100,"error_msg":"PARAM : Either photo_id or photos must be specified","error_data":null}
and photo_id is 100% present.
It is characteristic that users with such an error cannot upload photos to their albums even manually - everything freezes on "loading in progress".
"Informally" I position the error as a certain limit on the number of photos, however, there are cases when the error persists for several days,
Could you tell me how to interpret the error and deal with it?