j-and-d Try this: Locate profile folder: In thunderbird
- Help > Troubleshooting Information
- click on 'Open folder' button.
- Exit Thunderbird - this is important.
- delete 'permissions.sqlite' - read comment 10 in bug report.
- Open 'prefs.js' file using eg: Notepad or similar text editor program. Note: you could create a copy of 'prefs.js' on desktop as a temp backup in case you make a mistake.
- look for preference 'mail.ui-rdf.version'
- Set the value to 14, so it looks like the line below - Note in Bug report they set Value to 14 and it successfully then upgraded to 17 .
- user_pref("mail.ui-rdf.version", 14);
- Save the 'prefs.js' file.
- Start Thunderbird.