User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Firefox/91.0

Steps to reproduce:

Open thunderbird, do a "mark all folders read" on all accounts

Actual results:

The red overlaid message count still shows a (1) for the main window in the task bar, this only happens when Windows10 setting for "use small taskbar buttons" is OFF.

Expected results:

The red circle should only be displayed when there are actually unread messages

If the Windows setting "display badges on taskbar buttons" is turned off, the overlay/badge is not shown.

Are you sure this is not an unread chat message? Also look at bug 1721063.

it's possible, I don't have a chat tab open, and thought I'd disabled my chat account since the freenode takeover, but I'll open the chat tab and see if it's related, thanks.

regarding BZ 1721063, I don't get any tooltip when hovering over the window, not to say 1 unread, or 1 new unread, seems a different issue.

I can't reproduce this, did you find anything in the chat tab?

The chat account was disconnected (but trying to connect in the background)

I disabled the auto connect, quit and restarted TB, no "badge"

Re-enabled auto connect, quit and restarted again, still no badge, and it hasn't happened again since. I'd say close it and re-open if it occurs again.

-> WFM per comment 6.

I have had the message count badge re-appear twice since saying it no longer happens

It shouldn't be chat related as I have now deleted the IRC account

Both times, I went to every account and did a "mark all folders read" that didn't remove the badge

no folders show any unread message count, or are bold

If I go into a random folder, and mark a single message as unread, the folder goes bold and shown an unread count of 1, the badge remains, I then read that message and the badge disappears.

Once the badge has gone, marking a single message as unread makes the badge reappear, and reading the message makes it disappear again.

Becoming reasonably convinced this occurs when an email is received, the badge applied, then it is moved to Junk and marked as read, but the badge remains.

Yes, that's it

Twice I've cleared out my junk folder, and each time I saw the red (1) there was a new junk item in there.

I've found a way to reproduce it, will make a fix tomorrow. Thanks.

Because _updateUnreadCount is an async function and can be triggered frequently, call itself one more time when needed.

Pushed by mkmelin@iki.fi:
https://hg.mozilla.org/comm-central/rev/a3b326bd35ef
Make sure badge unread count reflects the current state. r=mkmelin

Comment on attachment 9236759 [details]
Bug 1725674 - Make sure badge unread count reflects the current state. r=mkmelin

[Approval Request Comment]
Regression caused by (bug #): bug 715799
User impact if declined: New mails automatically marked as junk still counted in the badge
Testing completed (on c-c, etc.): c-c
Risk to taking this patch (and alternatives if risky): low

Comment on attachment 9236759 [details]
Bug 1725674 - Make sure badge unread count reflects the current state. r=mkmelin

[Triage Comment]
Approved for beta

Thunderbird 92.0b3:
https://hg.mozilla.org/releases/comm-beta/rev/06b52dca1a7d

Comment on attachment 9236759 [details]
Bug 1725674 - Make sure badge unread count reflects the current state. r=mkmelin

[Triage Comment]
Approved for esr91

Thunderbird 91.0.3:
https://hg.mozilla.org/releases/comm-esr91/rev/802df9da4ec2

Picked up 91.0.3 on release channel, confirm fixed, thanks all.