You are not alone, there are a couple of other folks reporting basically the same thing. I have no idea why.

What version is reported in the Help menu > About Thunderbird dialog. Does it report as "Up to date" there as well?

Thank you for getting back to me. I lost the initial responses to my inquiry in an avalanche of e-mails.

My current version of Thunderbird is 68.1.2 (32-bit). The application tells me that I'm up to date, but I still get the same alerts. I don't get them every day, it seems to be random. So far, today seems to be an alert free day, but there is no telling what will transpire later as the day wears on.

By the time you read this I will have updated this app 3 times...

See if the procedure here eliminates the alerts. The current version is 68.2, so the notifications may be valid. The status of updating from Help/About TB or autoupdates is currently an off and on affair.

sfhowes

Thank you for contacting me and providing more information about this issue. I wish I could, at this moment, confirm that the latest fix was exactly that, a fix. Unfortunately the update alert has struck again. I've installed at least 4 fresh copies of Thunderbird to no avail.

Thanks, Mike

Are you using Kaspersky ?

Hello Wayne,

Yes I have Kaspersky. Should I remove it or just disable it and reload Thunderbird?

I thought I had this thing solved. I disabled Kaspersky, loaded the update then enabled Kaspersky. It seemed to have worked for a couple of days then I got that alert again.

I'm also having the same problem. I have 68.2.2 and I also use Kaspersky. Why won't the update just install itself? Why is a download required every time?

Workaround for Kaspersky users:

https://support.mozilla.org/en-US/questions/1271866?page=2#answer-1266662