There was a null pointer issue that was tripping up enough people with 3.0.3 that I created a small 3.0.4 release to address the issue.
The issues fixed are:
- CORE-1423 - NPE in ForeignKeyComparator
- CORE-548 - GenerateChangeLog generates invalid XML/SQL for mysql tables with autoincrement and compound PKs
with CORE-1423 being the one most people were running into.
You can download 3.0.4 from http://liquibase.org/download and through the maven repository system once it gets mirrored through.