I was running Thunderbird 86 beta. It has problems with hyperlinks so I downgraded to stable release 78.7.1 which required me to create a new profile because the 86 beta profile can't be used by the 78 release. I didn't want to recreate my address book manually in 78 so I copied abook.sqlite from the 86 profile to the 78 profile. When I open the address book, none of the contacts appear. Oddly, I had made 3 contact lists in the previous profile and those lists appear, complete with the addresses of the contacts. I can edit the contacts that appear in the contact lists. But if I search for one of the contacts in the list, I get no results. If I start typing a contact name in a new message, the address is not found by Write. Is there a way to get all my contacts back from the previous profile? EDIT: I opened the abook data read-only to see what was there. All my contacts data is there but the address book doesn't display it except for the 3 lists mentioned above. EDIT: OS is Ubuntu 20.04 on Thinkpad E420; desktop is gnome. EDIT: In addition to abook.sqlite there is abook.mab.bak, a text file which seems to have all my contacts data in it also. A bit hard to read because of the format. EDIT: Found the problem, I think. The database structure for 78.7.1 abook has 4 tables - cards, list_cards, lists, and properties. The database structure for 86.01b does not have the cards table. Apparently this table is needed to list the contacts in the Personal Address Book. Is there a way to create this table from the properties table?