Upload some (>1) files that will cause the commons Abuse Filter to throw an error, for instance by adding an OTRS ticket without being in the OTRS group. A warning is displayed for each file, which indicates that the user can click "Submit" again in order to ignore the warning. However, when submitting again, only 1 (random?) upload is successful, the rest fail with the same error. In total, for n images, one has to click the submit button n+1 times. For large number of files, this becomes tedious.