I ended splitting the files, it appears that the error is due to repeated logins, long URLs, and another issue that I cannot debug due to not having access.
The server error is generic, even with modified url’s:
url of the request (removed my id from it): https://ncs-ds.avast.com/api/datastore/v2/3++++++++4
HTML Error: 413 Payload Too Large
response: Failed to write datastore. Partition exceeds maximum size
This error occurs even with only one login selected.
The Avast Team should give a more verbose error in the instance of the import instead of this generic error that makes impossible to give the correct feedback to the Avast Team
I’m going to copy this response to the correct forum
correct forum link: New Avast Passwords Manager error on importing - #2 by tlcd96