debug.log also generated after automatic update check in opera task scheduler, there's no solution to stop this, you can delete task scheduler, but sometimes debug.log reapear in opera folder with same message, new chromium + maybe webview also causes this logs to reapear, it started around few months ago, i found this logs in many folders, but main folder is operagx, sometimes desktop+utorrent folder, or documents, so this is common problem probably, it always says same thing in the log:
Check failed: false. NOTREACHED log messages are omitted in official builds. Sorry! probably it is fixable

I have same issue, but with bookmarks too

today my pc was messed up by a windows update conflicting with something (my guess)

now I cant sync anything. it says synced but nothing is synced!

this is affecting my work

@musicollector It looks like this:

1348acac-25fe-4280-a185-098df2720fb9-image.png

Clicking it opens the URL ms-windows-store://home in a new tab which crashes Opera.

Didn't test, but this might work:

Make a test standalone installation and close it. In its install folder, go in to the profile/data folder and delete the Bookmarks and BookmarksExtras files. Then, in the "Sessions" folder there, delete all files, and put copies (so you still have the originals just in case) of your old session files there.

If you're lucky, when you start that test Opera, you'll see your opened tabs. Then, you can right-click on a tab in the tab bar, goto "save", and choose "all tabs to a speed dial folder".

Then, goto the URL opera://bookmarks and use the drop-down at the bottom left to export the bookmarks to an HTML file.

Then, in your regular Opera, goto the URL opera://settings/importData, select "Bookmarks HTML file" in the drop-down, and import the HTML file.

Then, at the URL opera://bookmarks, right-click on that imported speed dial folder and choose "open all in tabs".