When importing a backup, import fails because comments are stored in the current config comments fail xml validation:

<?xml version="1.0" encoding="UTF-8"?>
<!--

___ Exported on ___________________

on : Tuesday, 9 December 2008 14:28:09 o'clock GMT
by : scottharman ( Scott Harman )
.
.
.
. [mail handler options]
handler.params : reporterusername=admin,createusers=true,catchemail=jira.mail@example.com,bulk=ignore,splitregex="/<jira.mail@example.com>|--\s\n|--n/"
manually cleaning these corrects the import.