2026-05 Security Update (KB5089549) (26200.8457)

  C:\Users\<user_name>\AppData\Roaming\Thunderbird\Profiles

I've been running TB for 10-12 years, generally with no problems. When I logged in on 5/13/26, I saw that Windows had run an overnight update: 2026-05 Security Update (KB5089549) (26200.8457) Thunderbird (version 147.0.2.0) was not running, although it had been when I slept the PC the previous night. Now, when I try to start TB it gives me the crash report dialog. Selecting the Restart option just brings me back to the crash report. In searching for possible causes, I see that this may be caused by a bad profile. So I open the profile folder with (run) %APPDATA%\Thunderbird\Profiles\ which in my case is: C:\Users\<user_name>\AppData\Roaming\Thunderbird\Profiles This is an empty directory. But if I go up one level to \Thunderbird there is a profile.ini file which contains (actual user ID replaced by <user_ID>: ----------------------------------------- [Install8216C80C92C4E828] Default=E:\Thunderbird\Profiles [Profile0] Name=<user_ID> IsRelative=0 Path=E:\Thunderbird\Profiles Default=1 [General] StartWithLastProfile=1 Version=2''' ----------------------------------------- "E:\Thunderbird\" is the correct location of my TB installation. In that directory is a profile.ini file that contains: ----------------------------------------- [General] StartWithLastProfile=1 [Profile0] Name=default IsRelative=1 Path=Profiles/<user_ID>.default ----------------------------------------- Directory "E:\Thunderbird\Profiles\<user_ID>.default" is present. But all of it's files are dated 2010 except Mail, dated 2016. Directory "E:\Thunderbird\Profiles" contains the ImapMail and Mail sub directories totaling about 25GB data. I don't know what the Thunderbird startup process is or if this all looks correct. Can someone give me a sanity check? If this looks normal, what else could be corrupted? Thanks in advance.