When trying to edit a "readonly" tag, in BC the `org.jbpm.process.core.context.variable.VariableViolationException` is raised as expected. 

Although, the message shown in Business Central is not friendly as you can see on the screenshot. 

The raised exception is fairly technical (what is ok): 

"00:56:03,918 WARN [org.drools.persistence.PersistableRunner] (default task-22) Could not commit session: org.jbpm.process.core.context.variable.VariableViolationException: Variable 'approved' in process instance '8' violated"

But then in business central, it gets a bit confusing. A suggestion is that we can try to find a way to fit a message that better describes that this action cannot be done simply due to a rule defined by the user in his/her the process and that it is not a malfunction on the product (like it might look like now).