Perhaps you want $DBI::errstr.   Carefully read the entire documentation for DBI.

(And, please note, I am not giving you a brush-off, “RTFM!!” response here.   There is a lot to read, and you really do need to read through all of it, at least once.   Because of the sheer volume of it, and because of the complexity of the thing that is being described, sometimes the jewel of information that you’re looking for is not in the first place that you looked.)