A customer of mine on web2 seem to not be able to view his custom error page on IE (Internet Explorer), they work fine on FireFox…
I was a witness that the actual page worked on IE a day ago and than suddenly stopped working. This is not a coding issue since it was tested with very simple php echo tags.
If friendy errors are enabled (Tools - Internet Options - Advanced tab - Show Friendly HTTP Error Messages), Internet Explorer will show the “friendly” error page instead of the one you made for error codes that it has such a page for, such as 404.
Supposedly Internet Explorer will always show the custom page, if it exceeds 512 bytes in size, but I’ve never tested this. If that doesn’t work, you will have to turn the feature off, or you will have to generate error pages that return the normal return code (200).