If, for example, when installing  dotnet40 via winetricks you get the following error:

$ winetricks dotnet45
Executing w_do_call dotnet45
------------------------------------------------------
error: dotnet45 conflicts with dotnet40, which is already installed.

Run the following command to override and force through change

$ winetricks --force dotnet452

These notes apply to Kubuntu 18.04 and Thunderbird 60.9.1.

After Google restricted access for LSA’s (Less Secure Apps) it was necessary to change the Gmail account authentication method from “Normal Password” to OAuth2. After this gcontactsync failed – after logging into Google and successfully allowing access to Contacts it was blocked. After extensively trawling the net for a solution one was found. This said the problem was due to Thunderbird being corrupted and the solution offered was a complete rebuild – drastic but it worked!

The rebuild steps are follows:

Save Update History

Save version history, using apt policy,, which might be needed to rollback later, e.g. when TB automatically updates when not desired.

$ sudo apt policy thunderbird
thunderbird:
  Installed: 1:60.2.1+build1-0ubuntu0.18.04.2
  Candidate: 1:60.2.1+build1-0ubuntu0.18.04.2
  Version table:
 *** 1:60.2.1+build1-0ubuntu0.18.04.2 500
        500 http://au.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     1:52.7.0+build1-0ubuntu1 500
        500 http://au.archive.ubuntu.com/ubuntu bionic/main amd64 Packages<<

Example rollback

$ sudo apt install thunderbird=1:52.7.0+build1-0ubuntu1

Backup Address Books

In Address Book export each address book in LDIF format to Desktop\Contacts. The exported files names take the same name as the address book, e.g. Personal Address Book = Personal Address Book.ldif

Exit Thunderbird

Ensure all Thunderbird windows are closed

Uninstall Thunderbird

Using Synaptic Package Manager search for “thunderbird” and mark for complete removal and apply

Rename Thunderbird data folders

mv /home/user/.thunderbird /home/user/.thunderbird 60.9.1 backup
mv /home/user/.cache/.thunderbird /home/user/.cache/.thunderbird 60.9.1 backup

This effectively wipes all traces of Thunderbird data.

Install Thunderbird

Using Synaptic Package Manager search for “thunderbird” and Mark for installation and Apply

Launch Thunderbird

Search for Thunderbird and launch. From launchpad right-click Thunderbird and pin it to Desktop icons and Search and Launch.

1. Add Google account by following the installation wizard
2. In Config Editor Edit > Preferences > Advanced > Config Editor set the following:
   • Set “app.update.enabled” to false to disable automatic updates!!!
   • Set “general.useragent.compatMode.firefox” set to true to prevent Google Calendar continually asking for passwords and allow gcontactsync to display Google contacts lists to sync with
3. Restore contacts in Address Book by importing saved address books
4. Add gcontactsync and setup sync’ing of required address books with respective Google contact lists – should work now
5. Add Provider for Google Calendar to synchronise calendars
6. Add other email accounts as required

Notes for installing Thunderbird manually

Download required version from Thunderbird Releases

Install as follows

$ tar -zxvf thunderbird-60.9.1.tar.bz2  #creates thunderbird folder off Downloads
$ sudo su
# mkdir /opt/thunderbird
# cp thunderbird /opt
# exit

Create Thunderbird launcher

$ kate ~/Desktop/Thunderbird.desktop

[Desktop Entry]
Comment[en_GB]=Thunderbird email client
Comment=Thunderbird email client
Exec=/opt/thunderbird/thunderbird
GenericName[en_GB]=
GenericName=
Icon=/opt/thunderbird/chrome/icons/default/default256.png
MimeType=
Name[en_GB]=Thunderbird
Name=Thunderbird
Path=
StartupNotify=true
Terminal=false
TerminalOptions=
Type=Application
Version=60.9.1
X-DBUS-ServiceName=
X-DBUS-StartupType=
X-KDE-SubstituteUID=false
X-KDE-Username=