We have come across a Bugzilla database with a project that fails to import, breaking with:

Error importing data from Bugzilla: java.lang.NullPointerException at com.atlassian.jira.project.version.DefaultVersionManager.getVersion(DefaultVersionManager.java:464) at com.atlassian.jira.util.BugzillaImportBean.createVersion(BugzillaImportBean.java:870) at com.atlassian.jira.util.BugzillaImportBean.createVersionFromVersionTable(BugzillaImportBean.java:785) at com.atlassian.jira.util.BugzillaImportBean.createVersions(BugzillaImportBean.java:767) at com.atlassian.jira.util.BugzillaImportBean.create(BugzillaImportBean.java:198) at com.atlassian.jira.web.action.util.BugzillaImport.doRun(BugzillaImport.java:150) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at
...

It turns out this is because there is a versions table record:

+-------------+-----------+
| value       | program   |
+-------------+-----------+
| unspecified | app:AUdIT | 
+-------------+-----------+
1 row in set (0.00 sec)

But the products.product column value is actually app:AUDIT:

mysql> select product from products where product like 'app:AUdiT';
+-----------+
| product   |
+-----------+
| app:AUDIT | 
+-----------+

1 row in set (0.03 sec)

The case difference doesn't matter to Bugzilla, because MySQL is case-insensitive. However the JIRA importer puts the product name in a case-sensitive map, and so it breaks.