Prometheus reports ' "INVALID" is not a valid start token "

[tarasmandryk]

Prometheus reports an error " "INVALID" is not a valid start token " for pgbouncer exporter endpoint.

We use such products versions:
pgbouncer - v1.16.2
pgbouncer exporter - v0.4.1
prometheus - v2.31.1

pgbouncer, pgbouncer exporter and prometheus are deployed on Kubernetes
pgbouncer and pgbouncer exporter are deployed as two containers within a single pod in its own namespace. Prometheus is deployed as a separate pod in its own namespace. There is network connectivity between all components.
When we configure port-forward for pgbouncer exporter we're able to browse exposed data:

However, it seems like Prometheus is not able to parse this data as valid.

Please advise me on possible directions for investigation of this issue.

[tarasmandryk]

Apparently, the root cause was a slash symbol at the end of the endpoint expression.