Hi there, and thanks for your question!

It's probably a safe assumption that you're referring to Microsoft Office format attachments (.pptx, .docx, etc) but I wanted to make sure before we proceed. Can you clarify this before we try to reproduce the problem?

Before this started happening, were you opening these files with MS Office for Mac, or a different program?

Thanks! It's a mac. they are Microsoft Office format attachments, .docx. Previously they would always open when clicked in MS Office for Mac.

Also .jpg s won't open.

Wierdly, .xlsx do open. .pdf s do open.

Ok, thanks for the additional info!

I'm curious if somehow your default apps were changed on macOS...

Can you please browse to a .docx file in Finder, then right click it, then choose "Open With." Does Microsoft Office appear on that list?

Please repeat this step with a .pdf or .xlsx file and let us know what your "Open With" options are for that?

Thanks!

It's strange isn't it.

Clicked a .docx file, yes, Microsoft Word.app (default)

Same with .xlsx file, Microsoft Excel.app (default)

same with .pdf, Preview.app (default)

thanks again

Thanks for that info! OK, we're going to get to the bottom of this...

Now, can you please open up Thunderbird's General Settings (Thunderbird -> Settings, or the gear icon at the bottom of the Spaces Toolbar). Make sure "GENERAL" is highlighted, and scroll down until you see "Files & Attachments." (I've attached a screenshot of what that looks like on my system)

Can you show us a screenshot of what's there? Do you see that "Microsoft Word/Excel" etc is selected for the various file types?

We will find the answer eventually!

yes, all seem fine there, see screenshot,

OK, let's try Troubleshoot Mode next. Troubleshoot Mode allows you to run Thunderbird with things like add-ons and certain custom settings disabled.

To run it: App Menu -> Help -> Troubleshoot Mode.

Leave the 2 boxes unchecked.

Select "Continue in Troubleshoot Mode" and then try to open the .pdf and .xlsx files from Thunderbird.

Any luck?

Thanks, I've got a meeting now, but `i'll get back to it later. Thanks for your help, much appreciated,

Okay, I tried that. Just as before, the .docx and .jpg files wouldn't open but the .pdf and in fact an .rtf one I added just to try did open.

I was having the same problem with the previous Thunderbird version, sorry don't recall the number but it was 102.--- . I thought updating might fix it.

thanks again,

Help/More Troubleshooting, Profile Folder, click Show In Finder, close TB, delete or rename handlers.json, the file that contains the list of opening apps for various file types, as shown in Settings. Restart TB, open an attachment to a message and set the opening app, repeat for other attachment types. This is sometimes necessary if the opening app, e.g. Word, Adobe, is updated.

Great, fixed it!

thanks very much. I really enjoy tracking down these fixes.