Is there any option to cancel an ongoing file upload on Trello?
There is no such option in the Trello UI. Anyhow, you can always close the Window. Also, you can disconnect from your internet connection for a moment, if you wish.
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.