http://<host>:<port>/dev is not reachable

Problem

The page http://<host>:<port>/dev contains useful reports and troubleshooting instruments, but sometimes it might be unreachable with the following error:

Forbidden
The server understood the request, but is refusing to fulfill it.

Cause

By design, only those users who have default admin role assigned are able to use /dev functionality. Other roles, even if they provide all available permissions, can't navigate to the http://<host>:<port>/dev page.

Solution

Log in under a user with the default admin role assigned, who can use /dev instruments.