Ensuring IE Shows Your Error Pages

Sometimes it doesn't pay to be efficient with your page size.

One example of this was when we needed to put up some custom error pages for the websites at work.

We were using Apache's ErrorDocument to return nice 404 and 500 HTTP error pages. However Microsoft Internet Explorer refused to show them, preferring to use it's own pages instead of ours.

It turns out that IE will ignore error pages with a size of less than 512 bytes and use it's own. So the solution is to make sure your error pages are 513 bytes or more in size.

This is detailed in Microsoft Knowledge Base item Q234807.