How can I get Chrome to display the HTTP error returned by the server rather than the "friendly" error:
Page could not be loaded The link you specified does not work. This may either be the result of temporary maintenance or an incorrect link.
Searching for the text of the error message suggests it may be an EPiServer error page, not a Chrome friendly error message. (There are many matches from episerver.com with that exact phrase.)
In the version of Chrome I have installed (Chrome 4.0), the friendly error begins with "Oops! This link appears to be broken" and contains alternative links, a Google search box, and the Google logo on the right side. You can turn it on or off by going to the wrench menu → Options → Under the hood, then check or clear Show suggestions for navigation errors.
This "feature" in Chrome is designed to replace 404 errors by a "friendly" error page for server error pages that do not exceed 512 bytes in size, so were taken by the Chrome developers to be "uninformative". Only from 513 bytes and up is the error page displayed exactly as sent by the server.
The "friendly" 404 error page is also disabled for https.
The problem exists since 2008, when the issue was started in
Issue 1695: Chrome needs option to turn off "Friendly 404" displays,
but was never fixed.
If you control the 404 page returned by the http server, just fill it up with comments so it exceeds 512 bytes, or you can use https. Otherwise, I don't know of a solution.
The friendly errors disappear when using the the developer console open with Ctrl+Shift+I (CMD+Option+I) and then reload the error page to see the error properly.
These days (post January 2012) Chrome will only show a friendly error page if the server returns an error page without a body:
Now we only assume error pages without any body at all (content-length: 0) aren't useless to end users.
There are Chrome extensions available, such as HTTP Headers, which will show the details of the response headers - including the Status code (which you can see at the top of the box in the below screenshot).