After deploying a package solution to the server, you are unable to edit rules in forms and the error message appears as below:
'Object reference not set to an instance of an object'
1. You are unable to edit rules on some Forms. For other Forms or Views you can edit the rules normally.
2. There are errors in the host server logs as below:
"SourceCode.Runtime.Services.Forms","1 RuleHelper utility was unable to retrieve friendly name due to the following error: Object reference not set to an instance of an object"
There are two workarounds to resolve this:
1. Stop the K2 server.
2. Backup the K2 Database.
3. Restart the K2 service.
4. Delete the Form that is causing the issue.
5. Re-deploy only the form from the package (there's no need to redeploy everything).
Consider rolling back to a previously working version of the Form: http://help.k2.com/kb001311.