This looks like a general Hibernate, not an Envers question, so please direct the question to the Hibernate forum.
Hi Brand Neu,
Don't know if you ever solved your problem, but found this thread, and a solution (atleast for my problem).
Had the same problem, after a lot of searching i'd found that my problem was with hibernate annotations on the class.
In my project i tried to insert (persist) a row into a MySQL database that had MediumText type field.
The class was annotated with @Lob for the MediumText field property, that caused the exception you mentioned.
Strange thing is that it worked for the project while I was using OpenJPA 2 on Apache Geronimo.
So basically Adam is right
Your solution solved my problem!
My class was also annotated with @Lob for an ntext-column (sqlserver) . Without this annotation - INSERT now succesfull!
Interesting- I'm only removed @Lob : same sql-driver-jar, same datasource-properties.
Removing the @Lob does not help when you want to store more than 4K on Oracle.
I have solved the problem with an hibernate property:
<property name="hibernate.connection.release_mode" value="on_close"/>
This is indeed a Hibernate topic but this thread is the first hit when you google the error.