Save a log of error messages, including which files were not uploaded. For some reason, the list evaporates too easily.
Just uploaded a bunch of files. 3 failed to upload. While navigating to confirm two of them, the list disappeared and I've forgotten what the third file was. No easy way to figure out which of hundreds of files I uploaded did not upload. I guess I'll find out some day the hard way, but it would be nice for the web interface to allow a more persistent list of uploads (for convenience and completeness) until acknowledged and removed (for security reasons).