Ugly error message on failed form validation during document creation

[gruentee]

$ node --version 
v6.1.0
$ npm --version 
3.8.6

Trying to create a new page without supplying a title leads to a blank page only showing Cannot POST /save.

When creating a document with a title and the other fields left blank one is redirected to a page saying the page could not be created. On the home page the document link to the non-existent page apperas as if it had been created successfully.

[wmhfly]

I too error
Cannot POST /save

Have you solved it?