Primary profile works fine. (TB 52.6.0 32-bit, PortableApps, Windows 10, Dell E6520) (DRIVELETTER:\PortableApps\ThunderbirdPortable\...) 2nd Profile has issues saving/modifying addressbook contacts in Personal Addressbook and other addressbooks. (DRIVELETTER:\PortableApps\ThunderbirdPortable2ndProfile\) SYMPTOMS Unable to modify contacts in Personal Addresbook Unable to modify contacts in other Addressbooks OK button on Edit Contact window, child windows of Addressbook window, does not commit/close window Clicking on the X to close the Edit Contact window works, and the Contact appears changed in the Address Book Window Closing the Addressbook window and re-opening shows the changes did not stick. So two primary symptoms - OK button on Edit Contact not working and any changes are not kept on reopening. FIX ATTEMPTS 1. Temporarily Disabling addons/extensions fixed this issue, but this is an unsatisfactory fix. I have the following Addons/Extensions - Check and Send, Display Contact Photo, Forward, Mail Merge, Mail Redirect, MoreFunctionsForAddressBook, MultiTemplateLoader, Provider for Google Calendar, Select Addressbook Text, ThunderPlunger. These are all present in the primary profile, so while it would be easy to say disable something, that really isn't the point. 2. I closed TB, renamed all abook*.mab and inmab*.mab files as *.old, and restarted TB. This did not fix the issue. 3. Checked that using the latest version of 2nd Profile, and as far as can tell, I am. Aside from going through each and every addon, what can be done to fix this, and what is the permanent fix? Thanks in advance