[Marco van Herwaarden]

That part of the manual is usefull in most cases with this error, but not in this specific case. The "out of the ordinary" in this specific issue is that it looks like the maximum value for this field is already reached and the database must first be inspected to see if there are any large gaps in userid numbering, then the auto_increment value must be reset to a suitable value and possibly some higher number accounts need to be renumbered or removed & recreated.