When attempting to add files as attachments to pages the action fails.

In some cases, the attachment is successful, but the result page is a single text string saying "The parameter is invalid." Going back to the page shows the attachment was successfully uploaded and attached.

In many cases, however, the attachment fails (sometimes on the same file) and the result page is the Attach File page with a red bar over the File name box saying "You must enter a file to upload"... which I already did, along with a comment ...

The size is set at 10MB, and the file is only 52KB. It is regularly reproducable but doesn't seem to have a discernable pattern – sometimes I can attach files and it succeeds and then when I try to attach another it fails.

This is getting really frustrating for my users.