Drag and Drop into browsers

[Robert Palm]

Seems I cannot drag and drop files (.pdf, .txt,...) into FireFox or  
Chrome any more.

Your file couldn’t be accessed
It may have been moved, edited, or deleted.
ERR_FILE_NOT_FOUND
Drag & Drop into Intellij e.g. seems to work.
I use XFCE (thunar).

Worked before but I did not upgrade for 3 weeks or so...

Hints?

Thanks!