Following a recent update (May 25th, 2023) I have lost all my notes. I know Mozilla does not monitor the Notes extension actively and the corresponding Github repo is archived (https://github.com/mozilla/notes). Mozilla also notified the users about the decision to discontinue this service: https://support.mozilla.org/en-US/questions/1328311. However, I found the "Notes add-on" useful, and kept using it. Finally with a sudden update in late May 2023, I have lost all my past notes. While searching for possible solutions for the data recovery, I came to find the following solution by " jscher2000". # https://support.mozilla.org/en-US/questions/1390845 # https://support.mozilla.org/en-US/questions/1322197#answer-1384732 However, it was reported that though majority of the data was recovered by applying the technique above, lost notes were not among them: https://support.mozilla.org/en-US/questions/1390845#question-reply For anyone with similar issue I am describing below what worked for me. Following the suggestion by "jscher2000" I first generated the "Old Firefox Data" folder on my desktop. This is how I did that: From the Firefox browser window, click on ''Help -> More Troubleshooting Information -> Refresh Firefox '' and follow the instructions. After creating the "Old Firefox Data" folder you will be able to see one, or multiple, "profile folders" therein. On my system I was able to see multiple "profile folders". Next, type "about:profiles" in the URL space of a Firefox browser. I saw only a single profile (the default profile) on my screen that followed. Next, you need to "create a new profile" and point the system to one of the "profile folders" inside "Old Firefox Data" folder. Lastly, hit the "Launch profile in a new browser". If you can not see your old notes, try with another profile folder inside "Old Firefox Data" folder. This is what worked for me (Mac OS). If there is any better solution please suggest that.