I've read this problem in some similar threads, but I think it's not exactly the same issue. I updated to v55.0.3 a couple of hours ago (I do not recall which version I had before). I had 41 opened (kind of important) tabs, and after updating, all of them (BUT the first and the last one) appeared blank. No title, and no content when I tried to open them. I chose to update because I had an issue of not being able to create new bookmarks (I have not searched yet about this issue). Restoring (renaming) recovery.js and so on did nothing: I kept getting blank tabs every time I started Firefox. Then, I found the file containing the automatic tabs backup when updating, opened it in Firefox as a .json file, copied MANUALLY every one of the 41 URLs and reopened every single one of them... Even the bug of not being able to create new bookmarks was fixed! However, when I restarted Firefox, the tabs were blank again... I found out this would happen with every new tab restored. I tried updating to v56, same problem. I installed v54 and this problem was gone. But the bookmarks bug was there again, haha (I'll google about it right now, but the one that worries me the most is the blank tabs bug)... Any ideas? Thank you in advance!