I got my calendar entries to re-appear after upgrading from 78.14.0
(64-bit) to 91.2.0 (64-bit). Win 10 21H1. On 78.14, I deleted the few
tasks I had as per the above remark, and exported the calendar to
Home.ics. After the 91.2 upgrade, my Home calendar was empty. I then
added a new local calendar
This issue is closed for me. I uninstalled 91.2.0, deleted the
Roaming>Thunderbird directory, and re-installed 91.2.0. I was then able
to import my 78.14.0 Home.ics file into the default Home calendar. Then
I just had to re-add my few tasks. And also import my address book .csv
files. And copy in a
