Customise : You don't have permissions to access this page

I want to change the error message to a custom message more relevant for guiding the user to perform the necessary actions to gain access to the page. Can someone please help with how this can be edited?

Unfortunately, you cannot edit it.
You can make it a router page, and in the router function check the permissions and redirect to your own “No Permission” page.
But maybe it’s too much hussle.

By the way, I submitted a feature request for this page customization on Nov 28, 2018 (!!).
3 years have passed and yet…