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

Not excatly! We don't use the autocompletion function on a list form, rather on a custom webpart we've placed on the welcomepage of our root web. So the the issue might be the assumption that the autocompletefunction is used only on list forms.

<script type="text/javascript">
$(document).ready(function() {
$().SPServices.SPAutocomplete({
sourceList: "Projects",
sourceColumn: "Title1",
columnName: "tb_ProjectTitle",
numChars: 3,
ignoreCase: true,
WebURL: "/",
debug: false,
filterType: "Contains"});
});
</script>