Are there Sync error logs available?/

You can open about:sync-log via the location bar to see if there is a recent log available. You can upload a recent log if the log is too big to put in a reply.

• https://pastebin.com/

Refreshing Firefox didn't work, and neither did reinstalling it.

However, after checking the error sync logs on about:sync-log, I determined a network related issue was inhibiting Firefox's syncing. After some tests, I concluded that BitDefender AV Free Edition was the cause of the issue.

Firefox is now able to sync and Send Tab to Devices successfully after uninstalling BitDefender AV Free Edition. Which, by the way, also caused issues with SSL certificates giving me PR_END_OF_FILE errors.

Resolved.

cor-el said

Are there Sync error logs available?/ You can open about:sync-log via the location bar to see if there is a recent log available. You can upload a recent log if the log is too big to put in a reply.

• https://pastebin.com/

Thank you. I found out about the logs earlier today and it helped me solve the issue.

I will provide my logs for others' reference: FF error sync log

The log looks like a login error where Sync wasn't able to write the Sync credentials to the Password Manager to be able to login automatically.

Did you confirm that this was the problem?

cor-el said

The log looks like a login error where Sync wasn't able to write the Sync credentials to the Password Manager to be able to login automatically. Did you confirm that this was the problem?

I'm fairly certain it was. I've restarted Firefox a number of times to force a sync each time and it hasn't produced an error sync log. And no issues anymore with syncing in general that I can see.