Scraping of metrics fails with 500 Internal Server Error on v0.21.0

[iamejboy]

What version of Knative?

0.21.x

Expected Behavior

Scraping of metrics to knative components should not fail.

Actual Behavior

Returns 500 Internat error

An error has occurred while serving metrics:

3 error(s) occurred:
* collected metric "activator_request_concurrency" { label:<name:"configuration_name" value:"test-e2e-serving-sample" > label:<name:"container_name" value:"activator" > label:<name:"namespace_name" value:"knative-system-apps" > label:<name:"pod_name" value:"activator-848d58cc8-bmsrg" > label:<name:"revision_name" value:"test-e2e-serving-sample-00001" > label:<name:"service_name" value:"test-e2e-serving-sample" > gauge:<value:0.9282982149032333 > } was collected before with the same name and label values

Steps to Reproduce the Problem

Keep running the knative cluster with workload.

[novahe]

I think this is the same issue with #10421. you can try 0.22

[nak3]

Yes, agree with @novahe
Please feel free to re-open if you have seen the issue on the latest version.