Look on your desktop. Do you see a folder called; Old Firefox? Look inside. Look for the folder with the latest creation date.

https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Thank-you for the answer. I found the latest profile/places.sqlite file and I used it. My bookmarks and History are now available. Living in France the folder was named "Anciennes données de Firefox".

What reason did you have to refresh Firefox ?

It was suggested by Firefox : "It seems Firefox is slow ...." and in fact it was slow.

Yeah, I was already expecting that.

Note that such issues can be caused by problems with places.sqlite or other files in the profile folder, so be cautious with transferring data from the old profile.

How large is this places.sqlite ?

The size of places.sqlite is 25.6 Mo. I don't know if it's big or not.

I'm surprised that the size is the same for the Old Firefox file and for the new, generated by Refresh.

The only visible difference is that the Old works but not the new one.