What version of Oracle are you on?
If it's a version before they changed the error text, then you might need to do something along the lines of what K. Tsang mentions, and check column info against the data to find the mismatch.
To be honest,
you should be validating the data before it even gets here, though I realise mismatches can be introduced between the validation info and the actual database...then again, integration tests should pick those up.