What means: File Upload Not Allowed Exception?

I made a small mod to two forms in a working web app. On my first test, when I tried to save my changes to a normal document, the server gave me a 500 error and logged:

HTTP Web Server: File Upload Not Allowed Exception [/FOLDER/ourdb.nsf/ourview/ourkey?EditDocument&Seq=1]

The next time I tested, it worked OK. I just want to know: What made the log message appear - What was the problem?

ackground:

The document has an upload control.

The document’s save button does not submit() itself. Instead, it uses JavaScript to pop up another window. The user makes some choices there, then a button in that window kicks off the submit with JavaScript:

window.opener.SubmitDoc();

The JavaScript routine SubmitDoc() actually does the form.submit() to save the changes.

Found same msg w/ a possible fix in Domino.doc forum

www-10.lotus.com/ldd/ddforum.nsf/ 0/f513c7c99fcd4c0785256ed10077607a?OpenDocument