Having already experienced terminal problems with Thunderbird under Ubuntu Studio 22.04 LTS, I opted to install Betterbird 115.17.0-bb35 (flatpak) in my fresh installation of Ubuntu Studio 24.04.1 LTS. I followed the instructions in the README on github to migrate my 9.5GB non-flatpak Thunderbird profile to betterbird. However, betterbird spent hours re-downloading everything. On every subsequent start, the downloading starts over again form scratch. In addition, the numerous folders that I had under Local Folders are gone. Instead, there is one folder which contains a bunch of messages that do not belong there. I have tried numerous workarounds from various sources on the web. My last experiment consisted of starting betterbird with the "-purgecaches" option using a profile made by copying my old Thunderbird profile but excluding: * everything with "cache" in the name * all .msf files * all empty files and directories However, the results were the same. Unfortunately, I don't have a recent enough backup of the profile to be useful. The profile contains only IMAP accounts and Local Folders. What is the best way to get a working new profile containing as much as possible of the data form the old one?