Error 1037

This error indicates that the rewrite rule expression could not be evaluated.

Common cause

There are several causes for this error, but it can mean that one expression element contained an undefined value when it was evaluated.

For example, you get a 1037 error when using the following URL rewrite dynamic expression and the X-Source header is not included in the request:

http.request.headers["x-source"][0]

Resolution

Make sure that all the elements of your rewrite expression are defined. For example, if you are referring to a header value, ensure the header is set.