It is a long story, feel free to skip to the next paragraph. A customer reported JBPM-701 because they had a problem similar to yours, only with Job exceptions. We were about to release a new minor version of jBPM (3.3) which was a good opportunity to change the type of VARCHAR(4000) columns to TEXT. In the end the 3.3 branch was canceled and we ported the changes to the 3.2 branch. Some releases were made with the new schema (3.2.4, 3.2.5, 3.2.5 SP1) until it became a barrier for customers to upgrade, despite assurances that JDBC drivers handled the change from VARCHAR to TEXT transparently. The jBPM 3.2.2 schema was restored under JBPM-2056 and delivered in 3.2.5.SP2.

There is no way to insert strings larger than 4000 characters unless you change the related column to TEXT or increase the length. Provide your own copy of the hibernate configuration and specify an alternate mapping document containing the column type change. That was the resolution to JBPM-2057.

At some point I introduced a typedef which could easily be switched from VARCHAR to TEXT. That got lost among the compatibility restoration storm. With that, you'd only need to override the mapping resource containing the typedef.