Do you have the TB profile folder as an Exclusion in Defender? If not, does the attachment process change if you add the exclusion? The default location is:

C:\Users\username\AppData\Roaming\Thunderbird\Profiles\8charstring.default

AppData is hidden by default.

If none of that makes any difference, does it help to run TB in safe mode? Hold Shift when you launch TB.

I did not have anything excluded in defender. so i added that folder as well as the process "thunderbird.exe" neither changed the problem. I had already tried safe mode. That didn't work either :(

Does drag and drop from File Explorer to a new message window (to the right of the address area) work? What are your startup apps (right-click the Start button, Task Manager, Startup tab)? When problems arise after TB updates, it's often due to some background app becoming incompatible with the update.

It is a problem of the new windows 10 1909.. uninstalling Kb4517245 I've solved it How I can report this to thunderbird since the crash reporter do not appear? Thanks

Bug reports are submitted to Bugzilla:

https://bugzilla.mozilla.org/enter_bug.cgi#h=dupes%7CThunderbird

If you post there, you will be asked about details such as the ones in my last reply, i.e. startup apps, result in Windows safe mode etc. I haven't noticed any issues with attachments here in W10 1909. If you find crash reports under Help/Troubleshooting, post the URLs here.

Hi Alpingio, Thanks but I had geeksquad completely delete the windows 10 update in case that was it & it's still happening

Starting Windows in safe mode is a good way to test if the problem is due to 3rd-party startup apps or driver issues:

https://support.microsoft.com/en-ca/help/12376/windows-10-start-your-pc-in-safe-mode

Hi sfhowes, I can drag & drop from file explorer from my "documents" folder.

here are the list of startup apps

Thanks for your help

Hi sfhowes. I can attach documents in safe mode. now how do i figure out which app or driver is causing this problem. Thanks

There are a couple of items that may affect TB: Intuit Data Protect, if it's backing up the TB profile folder, and CCleaner is a perennial problem with TB. CCleaner should be set to not apply to any part of TB. The benefits are negligible and the side effects can be significant and annoying.

Windows safe mode will be the best test of the startup interference, if any. Hard to see how drivers could affect the attachment picker, especially if drag and drop is working.

andrea said

Hi sfhowes. I can attach documents in safe mode. now how do i figure out which app or driver is causing this problem. Thanks

You can disable the startup apps a few at a time until you find the source, if an app is the cause (start with the ones mentioned in my previous reply). If it's drivers, I doubt the Canon, Realtek, touchpad or audio drivers are to blame. It might be the graphics driver: when I updated to 1909, the HDMI video output stopped working, but downgrading the graphics driver fixed it.

Hi sfhowes. I end up deleting cc cleaner & disabled all the startup apps (just for fun) and it still does not work. :(

Not sure I understand all that you are saying concerning the graphics driver. I have not installed the windows new update yet. So hopefully that same problem u had is not my problem too

When you ran Windows in safe mode, besides bypassing the startup apps, a set of basic drivers for video, audio etc. were loaded, e.g. MS Basic Display Adapter for the video card. In your case, I don't know which device driver is causing the problem, and if it's necessary to upgrade or downgrade that driver. In my case, the remedy was to install a W7 video driver that was older than the existing one recommended by W10; there was no newer version available through Windows Update, as support for the hardware has ended.

Andrea, I've force the updated Thunderbird to 68.2.2 and with WIN 10 1909 I've no problem

I just started having this problem. I have Win 10, Thunderbird 68.5.0. Fairly clean installation. It has been working fine for years and started having the issue a week ago.

When attaching a Word or Excel document using the button, Tbird freezes and shows not responding. I can attach a *.txt file or a *.pdf file fine. I can drag a document to the message attach and it works. I can open the doc in Word and select sharing/email and it creates a message in Tbird that works ok.

I restarted TBird in safe mode, and the same problem comes up. I restarted win 10 in safe mode and it now works. At first I thought is was Kaspersky, but Tech support recommended to disable Kaspersky and see if that resolved the issue, but it did NOT.

I disabled most startup items, but am still stuck with the problem. Was there some recent update to TBird that would cause this issue? Thanks for any help you can provide.

Don