This should go through Resilient support, probably not the Community
@Alexandr Lebedev.
I imagine this occurs when you attempt to escalate an Offense to Resilient?
I'd guess you have an issue in the template you're using (which would indicate a defect since it didn't alert you of the issue when you saved it and should be reported to Support). I bet you have something strange in the template like {{incident.set}} ... I have not seen this error before.
Support will likely encourage you to check the developer console for more information on the error and/or ask for the template export.
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Jared Fagel
Cyber Security Analyst Intern
Public Utility
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