What's the authentication method for the incoming and outgoing servers in Account Settings? It should be OAuth2.

For the Gmail account it is indeed 0Auth2. As for my other accounts, each is just listed as "Normal Password". Incidentally, all the other accounts are working fine.

P>S. I should perhaps explain that I have 4 email accounts, each from a different provider on my Thunderbird. .

Do you have 4 smtp servers defined, and is each account set to send on an smtp that has a matching User Name? Possibly there is a non-gmail account sending on a gmail smtp. Select an account in the left pane of Account Settings and look at the selection for Outgoing Server (SMTP) in the right pane.

Hello. Many thanks for your latest reply. It came in overnight here in the UK. I guess that this will reach you while you are asleep. I have checked my other accounts for the smtp in the way you suggested with the following results. Ionos : auth.smtp.1and1.co.uk BT mail : mail.btinternet.com Microsoft Outlook 365: smtp-mail.outlook.com which look right as far as I can tell. To complete the list , the smtp for the Google account is showing as smtp.gmail.com William

Do you sync a calendar or address book with Google? If you do, either one would require OAuth2 authentication anyway, not request a password like in your picture. Check that there isn't some kind of password manager, that comes with some security apps, that is issuing google password requests.

I used to, using Provider for Google Calendar, but after taking out a subscription to Microsoft 365 in April 2022, I deleted that add-on replacing it with Tb Sync and Provider for Exchange Active Sync. There were some issues with them following the upgrade to Thunderbird version 102 but after the Author updated Tb Sync they went away of their own accord. The only security software that I have loaded on my Desktop is Canonical's Live Patch and I have no idea how to interrogate it to understand if it might be issuing Google password Requests.

You deleted the provider, but did you delete the calendar in the list on the calendar tab? (right click unsubscribe) I think perhaps not.

Hi Matt Thanks for the suggestion but I did delete Google Calendar from the list in the calendar tab. I have just checked and these are the calendars currently showing in the list and in this order: Home; Derby County (Read only); Outlook Calendar; Outlook Birthdays; Outlook Facebook Birthdays; Outlook UK Holidays; and Outlook England Soccer Internationals (Read only). William

All I can suggest is you right click the two read only calendars and check they are not hosted at google.

However while I jump to the conclusion that it may be a calendar, there is also the chance that it is an address book as those are not auto detected along with calendars when account are created. So you might want to check the address book for a google contact type list.

Only the Derby County Calendar lists a location in the properties list. It is https://ics.fixtur.es/v2/derby-county.ics. I cannot tell if this is hosted by Google or not. I am not clear what I should be looking for in the Thunderbird Address Book. I did create a contact list for the Committee members of the group the Google account is used for, but this appears only as a sub list in my Thunderbird personal address book. It has never been set to appear in contacts in Google web and does not do so (I have just checked), so is presumably not attempting to sync with it.

In case there's some leftover Google account in an add-on, see if the request is present in safe/troubleshoot mode (Help/Troubleshoot Mode...). Provider, CardBook, TbSync etc. can sync Google calendars and Contacts.

If it becomes a significant issue, you could always create a new profile and (carefully) add the mail accounts and calendars.

Many thanks for the suggestion, sfhowes. Sadly it was not the answer. I ran Thunderbird in trouble shooting mode with all addons disabled. No sooner had Thunderbird loaded but the offending error message flashed up! I think you are hinting at the possibility that the profile has become corrupted. I think you may be right. However, balancing the risk of making a mess of creating a new profile and the irritation of the false error message, I am inclined to stick with the current profile unless the error message become far more intrusive. Many thanks, anyhow, to both of you for taking the trouble to consider my problem and provide me with possible solutions. Wishing you a Happy New Year. William

Have a look in the mo0re troubleshooting information on the help menu.

Look at the mail and news accounts, calendars and chat accounts and make sure you have nothing google configured in there. While google no longer has a chat in Thunderbird there may be an old account hanging around.

Hi Guys I think I have solved the problem. I was determined to crack it and followed up the suggestion that it could be caused by a legacy address book. I initially tried this but could find nothing. Clicking on the properties of each address book would simply cause a screen giving just the name of the address book and nothing else to pop up. I gave up but came back to it a little while ago. I noticed an item in the list for the innocuously named " Address Book" (I could have sworn I had not seen it before.) Anyhow, I clicked on the properties for this and lo there was the web address for this address book and it was obviously the address for Google Contacts. I duly deleted this address book and so far the offending error message has not reappeared. Hopefully I have seen the last of it. Thank you both for showing me the way to a resolution of the issue.