Thunderbird 158.0 Could not edit appointments - OSX fix?
Was unable to edit appointments attempts placed a previously unknown dialog box. Search for info found one person advised Select Calendar (tab), edit, calendar properties and uncheck the read only box.
In my case the box was already unchecked, checked it, tried it, same result. Unchecked it, tried it same result (not able to edit).
Next I thought maybe some data location is not being changed. So I closed all files, shut down (not a restart) my machine, and restarted it. Opened Thunderbird and tried to change an appointment, did not work. Went to Calendar (tab), edit, calendar properties and found the read only box checked. Unchecked and all seems back to normal operations now.