The file that I was trying to upload in the screenshot was the same as [[commons:File:21 February 2008 lunar eclipse from Los Angeles, California.jpg]]. It turns out any attempts to upload a file have the same name as a file already present on commons produces the same error. Perhaps a less technical error message to the uploader, something generic and probably customized (another MediaWiki: file?) would point out the source of this problem.
Version: unspecified
Severity: enhancement
URL: http://test.wikipedia.org/wiki/File:Upload_wizard_test_1_by_TeleComNasSprVen.JPG