Most likely, there is some issue either on the object level or DB level with the externalisation field (since removing it helped). Most likely it was renamed or the compilation didn't go successfully when adding it. To fix the issue you can try doing the following steps: Generate source code for all -> Compile all -> Update DB structure. If these steps won't help please contact the support team at support@creatio.com. The issue would be easier to analyze after seeing the full log as the message in the UI doesn't reflect where exactly the error occurred.