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Question

Error: "triggerIncident response status:400, error:Incident could not be assigned error: undefined"

  • January 30, 2026
  • 1 reply
  • 8 views
A

I have a Pager Duty incident alert rule which is:

  1. A valid Service Offering (in ServiceNow)
  2. A valid Assignment Group  (in ServiceNow)
  3. A P1 or P2 incident

I have had two incidents in the past few weeks where the integration failed with the error:  Error: "triggerIncident response status:400, error:Incident could not be assigned error: undefined".

 

Some incidents in between have created the alert from Service Now to Pager Duty and the Incident Rule ran fine, this morning I had another one.  I would like to understand why this is an intermittant issue before it becomes widespread.

Pager Duty has been configured out of the box, no customisations, the same for Service Now and imported the Services, Assignment Groups and users the recommend way (from Service Now via the API/integration).

1 reply

danieljcafonso
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  • danieljcafonso
  • Community Manager 💚
  • February 2, 2026

Hey ​@AlexG hope you are doing well!

That 400 (“Incident could not be assigned”) usually means the payload tried to assign to someone/thing PagerDuty can’t use at that moment. Since it’s intermittent, it’s typically data/mapping-dependent.

Here are some likely causes:

  • The “Assigned to” user in ServiceNow does not map to an active PagerDuty user.
  • The PagerDuty service has “Restrict incident assignment to users in this service’s team” enabled and the chosen assignee is not on that team.
  • The Assignment Group maps to an Escalation Policy that has no on-call person at that time.
  • Combined mappings (Service Offering, Assignment Group, Priority) sometimes pick an unmapped assignee or an unmapped Escalation Policy.

What to check now?

  • In ServiceNow: If “assign to user when Assigned to is set” is enabled, confirm every possible assignee maps by email to an active PagerDuty user.
  • In ServiceNow: Verify Assignment Group and Service mappings for the incidents that failed.
  • In ServiceNow: Open the PagerDuty app logs for a failing call and copy the full PagerDuty response and the request identifier header value.
  • In PagerDuty: Confirm the service has a valid Escalation Policy, the Escalation Policy has on-call coverage at the failure time, and if assignment is restricted to the service team, the intended assignee is on that team.

Let me know if any of these things helped! 

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