I am migrating a project from Struts 1.1 to 1.2.9. I followed the instructions at http://wiki.apache.org/struts/StrutsUpgradeNotes11to124 but I am getting an exception on startup and can't pinpoint the problem. I'm wondering if anything has changed that wasn't documented.
I'd make sure you're using the validator-rules.xml it suggests, other than that, it's hard to say--almost certainly an issue with one of your validation files.