Is there any option to cancel an ongoing file upload on Trello?
There is no option to cancel or escape the upload at this time. One fast and simple solution is:
- Resize your window so you can see your desktop.
- Drag/drop a small picture or text file from your desktop onto that "drop files to upload" UI.
- Delete the file immediately after using the delete link.
This is possibly better than closing the window and losing your changes, or disconnecting your online connection.