The current release version is 38.7

So I assume your beta testing. Given there are some significant changes in V45, have you tried with add-ons disabled from the help menu? Often small things stop working with add-ons that are only sort of compatible with a new version.

My software just upgraded to 45.1.0 and I am not using any add-ons. Drag and drop worked fine until yesterday (when the upgrade happened). Is there a solution to this? Do the developers even monitor this forum?

Restart Thunderbird with add ons disabled and see if it works. You do this under the Help Menu.

Didn't I say that I had NO ADD-ONS? I've also restarted and wouldn't post a question if I hadn't done the basic steps of troubleshooting.

Excuse me. Good luck.

Anita said

Didn't I say that I had NO ADD-ONS? I've also restarted and wouldn't post a question if I hadn't done the basic steps of troubleshooting.

Congratulations you have no add-ons, safe mode is more than add-ons, but instead of trying with the support person you exercised your right to repeat what was not helpful.

Personally I suggest you start your own topic and actually explain what you have done with regards to diagnostics, not forgetting the operating system safe mode tests.

Oh and this is a support forum. So no the developers do not lurk here? They respond to bug reports, filed in Bugzillla. Not individuals experiencing difficulties on their personal setup., until we can establish the cause is actually a bug. Failure of the software to perform as you expect is not necessarily a bug. Although lots of people appear to think any failure of their expectations is a bug. It is not.

Matt, I was just annoyed that somebody posted to turn off add-ins after I had already posted that I didn't have any.

I found that I was having the same issue with other programs that allowed drag & drop. It turns out it was an issue with the last Windows 10 update. I uninstalled that update and drag & drop works again.

I am always amazed that people that already know it all even come here and ask a question.

Anita said

Matt, I was just annoyed that somebody posted to turn off add-ins after I had already posted that I didn't have any. I found that I was having the same issue with other programs that allowed drag & drop. It turns out it was an issue with the last Windows 10 update. I uninstalled that update and drag & drop works again.

That last is good information. Windows 10 really appears to be about as buggy a product Microsoft have released since Windows ME. But people are sill buying it and using it. It leaves my lost.