I just downloaded 2.1.30 from https://apps.ankiweb.net/, so I assume this is a stable release. After installing 2.1.30 whenever I try to sync I get the error message
and all changes couldn’t be synched to AnkiWeb.
The problem would be gone if I downgrade back to 2.1.26. Changes that can’t be synched on 2.1.30 would also be synched successfully after the downgrade. Doesn’t seem to have problem anymore if I stick to 2.1.26, but reporting this might be good.