Description of Hypertext Transport Protocol Error Messages (218155)

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In Microsoft Internet Explorer 4, when the Wininet.dll file cannot resolve a request, it displays an embedded Hypertext Markup Language (HTML) error message and a non-descriptive definition (for example, "Navigation Canceled" or "Unable to retrieve Webpage in Offline mode".) These error messages are a resource (res:) of the Shdocvw.dll file. A resource is HTML code that a program uses for display purposes that is embedded in a dynamic link library (DLL) file. In Internet Explorer 5 or later, these error messages are stored as a resource of the Shdoclc.dll file. When the error message is received it is replaced with a corresponding HTML template, which can contain any of the following types of information:

• Information about the problem.
• Information about how to correct or work around the problem.
• A link to the previous page.
• A link to Internet Explorer support page.
• A link to the same page so you can try connecting to it again.
• A link to a copy of the page from the cache (if an Application Programming Interface (API) is created).

The friendly HTTP-status error messages are stored in the following registry key:

   HKEY_LOCAL_MACHINE\Software\Microsoft\Internet Explorer\Main\ 
      ErrorThresholds
				

Internet Explorer 5 and later provides a replacement for the HTML template for the following friendly error messages:


There is a name value pair (for example, "404", 128) for each of the errors. The first value is the error code. The second value is the byte size value used by Internet Explorer 5 or later to detect when it should replace error messages with its own. Therefore, when the Internet Explorer 5 version of the Wininet.dll file obtains an HTTP error message, the Wininet.dll file determines if the HTML content attached to the HTTP error is a well designed Web page. This is based on the size of the page. The threshold value in the registry is evaluated for each error. If the Web page is small enough, it gets rejected, and the friendly HTTP-status Web page is displayed.

The HKEY_LOCAL_MACHINE key stores the computer's default values. The same key and value can be set in the HKEY_CURRENT_USER key to override the HKEY_LOCAL_MACHINE values on a per-user basis.

To disable friendly HTTP-status error messages, follow these steps:

1. Click Start, click Settings, click Control Panel, and then double-click Internet Options.
2. Click the Advanced tab.
3. Click the Show friendly HTTP error messages check box to clear it.
4. Click OK.

NOTE: Turning off friendly HTTP error messages disables only friendly HTTP error messages for HTTP error messages returned by the server (listed above). There are other friendly error messages that cannot be disabled. For example, DNS error messages occur when Internet Explorer cannot find a server. In this case, there is no page to replace so Internet Explorer 5 or later always displays a friendly "Page cannot be displayed" error message.