on question #2: https://ftp.mozilla.org/pub/thunderbird/releases/115.18.0/win64/en-US/ is the last version for win 7. However, I don't think the problem is there. Is this a POP account? If so, downloading on win 10 pc may have caused messages to be deleted from server, causing a request for mail on the other pc to come up short.

This is not what happened. First, I checked the server and there multiple new emails. Then I tried downloading the emails to Thunderbird v115.18 on a Win7 PC. That is when I get the "There are no new messages". I was able to get the emails on my Win10 PC using a later TBird 64-bit version.

Is there any reason v115.18 (32-bit) would generate "There are no new messages" when there still emails on the server? Something either broke or changed from 7/16/25 until the morning of 7/17/25.

Any and all help would be appreciated.

TC

something changed, but as you must already be aware Thunderbird has not updated as your operating system is not supported after V115. The Thunderbird 32 and 64bit versions are fundamentally identical, except the 64bit version uses more memory as data is 64bit long not 32.So what could have changed.

1. You antivirus gets an update in many cased every 10 minutes from a home server. There is a very high possibility that it has changed.

2. Your mail provider may have changed the sign in requirements for the server. Something like they have updated the security settings to something Windows 7 does not support perhaps.

Historically I have seen POP mail account report no mail when the antivirus has dropped it's load and just gone offline. The same could be true of IMAP accounts, I just have not seen it.

Microsoft regularly update the requirement to connect to outlook/hotmail/msn/live accounts. Their intepretation of oath in their "Modern Authentication is special to them, hence this article from 2024 https://support.mozilla.org/en-US/kb/microsoft-oauth-authentication-and-thunderbird-202. Some folk managed to get off that merry go round by using application passwords, but I understand Outlook is not longer allowing them. So the choice is oAuth or nothing.

Google have also been known to modify their connection retirements. I do not have any idea what mail provider you are using, you do not say. So I mentioned a couple of well known issues. But installing a 64bit version of the software is not going to be of much help to you is my guess. Just like reinstalling is rarely a method to do anything be waste time. Look for the real issue and in this instance I would be inclined to be looking at the antivirus. The longer an operating system is out of support the more antivirus programs attempt to compensate for unpatched vulnerabilities. The net result is usually a loss of connectivity and access to non browsing functions and sometimes even those.

I have a somewhat similar issue with Tbird 115.18.0 running on WIndows 7. In my case though the server is not syncing properly, and causing duplicate messages to be downloaded, which I can remove (at least with any tool I see for 115.18.0.

I am going to migrate the profile to windows 10 (I hope), but would like to eliminate all the duplicate messages before I do that.

I will also need to know what I need to do to make the profile compatible with windows 10 before migrating it.

The best advice I can offer is to install the same version of thunderbird on the new PC. THunderbird is more concerned with thunderbird versions than with windows versions. You can pick 115.18 here:

 https://ftp.mozilla.org/pub/thunderbird/releases/115.18.0/win64/en-US/  

Then, install it, start it, and then exit. And then, follow these steps:

Here is the link for moving a profile in Windows when installed in default location:

https://support.mozilla.org/en-US/kb/moving-thunderbird-data-to-a-new-computer

here is the info in brief steps:

1. ensure thunderbird is NOT running on old machine
2. enter %appdata% in search window on task bar and press Enter key
3. this should open windows file explorer in Appdata\roaming folder
4. highlight the Thunderbird folder and copy to external media
5. ensure thunderbird is installed on second computer and NOT running
6. enter %appdata% in search window on task bar and press Enter key
7. you should be in Appdata\roaming folder , copy&paste the exported Thunderbird folder there. This may prompt to overwrite an existing folder of same name. allow it
8. start thunderbird and all should be there