Works still here in DE in a profile connected to Sync (I do not use Sync with Beta, so can't test that).

Are you sure you are connected to Sync ? Does Synced Tabs in the sidebar work ?

Start Firefox in Troubleshoot Mode to check if one of the extensions ("3-bar" menu button or Tools -> Add-ons -> Extensions) or if hardware acceleration or userChrome.css is causing the problem.

• switch to the DEFAULT theme: "3-bar" menu button or Tools -> Add-ons -> Themes
• do NOT click the "Refresh Firefox" button on the Troubleshoot Mode start window

• https://support.mozilla.org/en-US/kb/diagnose-firefox-issues-using-troubleshoot-mode
• https://support.mozilla.org/en-US/kb/troubleshoot-extensions-themes-to-fix-problems

You can open about:sync-log via the location bar to see if recent Sync logs are available. You can upload the file to a website like Pastebin if you can't post the content of the file in a reply.

• https://pastebin.com/

I am still connected to Sync, and that is working properly from an end user point of view. I can still access tabs on my mobile device from the sync menu, and it is updated to my latest mobile browsing session. Sending tabs is an option from my mobile device to my desktop, however the tabs never appear.

I've been using Firefox with the default dark theme, and haven't added any new extensions in several months to trigger the change. Troubleshoot mode does not restore the Send Tab to Device menu option.

There are 35 instances of error-sync text files over the past few days, the largest of which I've uploaded to https://pastebin.com/jFCFGwCK Note that this was taken from a time when I wasn't actively using the computer, just had the browser left open.

Thanks for the support!

What items are selected for Sync ?

• https://support.mozilla.org/en-US/kb/how-do-i-choose-what-types-information-sync-firefox

You can also check Boolean services.sync.engine prefs directly on the about:config page.

This pref shows what items aren't included:

• services.sync.declinedEngines

You can open the about:config page via the location/address bar. You can click the button to "Accept the Risk and Continue".

• https://support.mozilla.org/en-US/kb/about-config-editor-firefox

Everything* is checked off and appears to be syncing correctly. I can bookmark a tab on one device, sync both devices, and the bookmark appears on the other device. What's missing is a context menu option to push a single tab directly from one device to another without having to re-sync both devices.

When I right click on a regular tab, one of the options is to Share. This option disappears when right clicking on the about:config tab, and rightfully so as that tab can't be shared beyond the local machine. Firefox is context aware and does not let the user share about:X tabs. It appears as though that behavior is occurring on all tabs for the Send Tab to Device option, as it does not display when right clicking on any tab.

Bookmarks History Open tabs Logins and passwords Addresses Credit cards Add-ons Settings

I'm having the same issue on Desktop for Mac. There used to be a Share symbol at the right end of my URL bar, next to the Reader View and Bookmark options. It hasn't been there for at least 2 months. I can still go to File > Share > Airdrop but the Send to Device option is nowhere to be found.

Also, sending a tab to my desktop from mobile/tablet is working just fine. It's just from desktop to another device. Sync is turned on and working more efficiently than before with no lagging or lost data/history.

My browser version is always kept up to date and my device sharing settings are set appropriately. I'm not a tech by any means, but I'm not a slouch either. I'm at the end of my savvy though.