for one Sharepoint 2013 site, I successfully managed to create a custom 404 error page by setting the site parameter vti_filenotfoundpage to the desired URL.
However, this does not work for another sharepoint 2013 site and I have no clue why.
Setting the same parameter shows now effect.
Also setting another parameter SPSite.FileNotFoundUrl doesnt do it.
Apparently I am not able to add the 'error page' to the content type: For the parent content type "Publishing Content Types" or "Page Layout Content Types" I can only select other options.
How can I map the error page (which is non-existent at the moment) to a custom page? Thanks!
edit: I assume to have a 15 Hive site (as the site settings URL contains .../_layout/15/...)
I created various files but none of them works (CustomError.aspx, PageNotFoundError.aspx as well as in Site Pages as in the site root directory).
I have site owner and designer rights (but no admin/collection). And I am working on a sub site (have only rights to this sub site).