Kubernetes Cluster Setup and other views report an error when Portainer is exposed over a subpath

[jamest-portainer]

Before you start please confirm the following.

• Yes, I've searched similar issues on GitHub.
• Yes, I've checked whether this issue is covered in the Portainer documentation or knowledge base.

Problem Description

When Portainer is exposed over a subpath such as https://tools.domain.tld/portainer some views in the Kubernetes management area are failing to load.
We have tested the following views that were failing, some others might be as well:

• Cluster setup
• Ingress creation (add via form)
• Namespace access view

Expected Behavior

No error should occur.

Actual Behavior

The following error is reported by the API (this example is from the Cluster Setup view):
{
"message": "Failed to check RBAC status",
"details": "the server could not find the requested resource (post serviceaccounts)"
}

Steps to Reproduce

1. Deploy Portainer so it is exposed over a subpath
2. Go to one of the views mentioned

Portainer logs or screenshots

No response

Portainer version

2.18.4

Portainer Edition

Community Edition (CE)

Platform and Version

Kubernetes

OS and Architecture

Any

Browser

No response

What command did you use to deploy Portainer?

No response

Additional Information

No response