Error message when you visit a Web site that is hosted on Internet Information Services (IIS) 7.0: "HTTP Error 412 – Precondition failed"

You have a Web site that is hosted on Internet Information Services (IIS) 7.0. When you visit the Web site, you may receive an error message that resembles the following:

The request is not completed because of the preconditions that are set in the request header field. In the request from the client computer, the If-Match request header field contains an entity tag. IIS cannot recognize the value of this entity tag.

To resolve this problem, examine the value of this entity tag to make sure that IIS can recognize the value.