How can you edit Confluence error messages?

Question

How can you edit the Confluence error messages such as

"Conflict

The server encountered an internal error or misconfiguration and was unable to complete your request."

or "The following error(s) occurred:

* A page can not be set as its own parent.
* A page already exists with the title 'Resources - ONE' in the space 'Line of Business'.

Felise Uy · Accepted Answer

For the Conflict error, I had to set my Apache 409 document. For the other error, not sure how to do it still.