Unable to Sync Anki without error message

Currently using Anki 2.1.30.

For over a year now every time I try to sync I get the error message:

“A network error occurred. Error details: ⁨HTTP status client error (400 Bad Request) for url ()⁩”

I am using an older version of Mac OS (10.10.5), which might be causing this issue.

Things I have already tried:
-Using Check Database
-Creating a new anki web account and syncing to that
-Using the debug console and plugging in the following code: mw.col.db.execute(“delete from revlog where type > 4”) mw.col.modSchema(check=False)
-disabling all add ons

None of these work, but plugging in that code into Anki does at least let me sync to anki web. If I don’t do that, then it tries to sync but just gives me the 400 error code. When I do sync to Ankiweb after using the debug console, it lets me sync, but the error message comes right back after I do another review.

Any help troubleshooting is appreciated!

You should really consider updating Anki, as we currently are at the version 2.1.54. Besides that, I would recommend not executing commands such as mw.col.db.execute(“delete from revlog where type > 4”) mw.col.modSchema(check=False) unless you know what you are doing (and do a backup beforehand), as it allows you to make any kind of changes to Anki’s database without restrictions, and without warnings if you were about to blow it up. Finally, since it seems a networking issue, do you have any proxy / VPN setup? If so, could you try disabling them?