@lukas-tresnak I found a manual solution. My old data was already in the path files. Type opera:about/ to find your path. It should be something like this: /Users/[YOURNAME]/Library/Application Support/com.operasoftware.Opera/Default
If you uninstall Opera, you probably either have "Default" or "Default.old" Check both and find the file named "bookmarks" and "bookmarks.bak" see if your old bookmarks are in there. If so, download opera again, copy the old ones from "default.old" and paste them in the new "default" file. Do all of this when Opera is not running.
