trying to upgrade my site from 1.50 to 1.56a as the force of running php7 comes in. but what a nightmare!

Anyhow, almost there, but for DPU have the constantly spinning wheel and the console error gives:

XML Parsing Error: not well-formed Location: http://localhost/ajax.php?cPath=443_...hod=dpu_update Line Number 2, Column 1:

any ideas at where i should be poking round for this? within the modules/pages jscript stuff?