Dynatrace workflow executed by service user not working anymore

[ftmazzone]

Hello,

Since the beginning of the week, the workflows executed by a service user are not running anymore and failing with the following error.

431: Request Header Fields Too Large
    at MetricsClient.query (file:///opt/sdk_modules/@dynatrace-sdk/client-classic-environment-v2@4/esm/index.js:14847:21)
    at eventLoopTick (ext:core/01_core.js:177:7)
    at async computeAvailabilityFor (file:///script.ts:118:20)
    at async default (file:///script.ts:21:9)

The failing API is the following : `/platform/classic/environment-api/v2/metrics/query?metricSelector=builtin`.
The same workflow is executed without issue with a "standard" user. The issue is only happening with service users.

I've read the Error when running DQL Query through workflow but do not know how to restrict authorizations for a service user and don't understand why it is suddenly failing as it worked without problem since 2025.

Are you aware of any change for the workflow or any permission required for the service user ? 

Thanks.

Florent

[sujit_k_singh]

Hi @ftmazzone 

The error 431: Request Header Fields Too Large is typically caused by the request exceeding the allowed HTTP header size.

In workflows, this is known to occur when the executing identity (particularly a service user) has too many permissions or scopes assigned. These permissions are included in the request context and can cause the header size to exceed platform limits.

Why it works with a standard user: Standard users typically have fewer directly-bound policies, they inherit permissions through groups, which keeps the token smaller.

Recommended actions: Review the service user’s assigned groups and policies. Reduce permissions to the minimum required scopes only.

Thanks

Sujit

[ftmazzone]

Hi @sujit_k_singh ,

Thanks for your reply. I've checked the audit, we did not change the permissions and it was working 3 weeks ago.
For this reason, I don't think it is related (directly) to the permissions of the service user. 

Thanks,

Florent

[sujit_k_singh]

Hi @ftmazzone 

Thanks for confirming. If permissions haven't changed then I am not sure what could be the reason, Support ticket is your best path here.

Thanks,

Sujit

[ftmazzone]

Hello @sujit_k_singh ,

Thanks.
I've opened a support ticket but they are also unsure about the issue. 😉 It looks like the old metric API is not working the same way as before as the new API is not impacted.

Florent