New Post: SPListNameFromUrl throws execption when used for a file stored in root folder

OK, so let me rephrase the issue so I'm sure I've got it.

You're using SPAutocomplete in a list form for a list in the root Web, i.e., "/". The function is failing in the call to genContainerId("SPAutocomplete", opt.columnName).

Can you please post your call to SPAutocomplete?

M.