I am looking for help with using proxy.ashx in Javascript API on one particular server at a client site. We have a GP service that the proxy is used to access (when request is more than 2048 characters).

I have configured proxy and it works fine on one of our server in house. Javascript API application can send request using proxy.ashx.

In another environment at our client site we get Error 500 -Unable to access the web page. But without the proxy we can access the page. Here are some test case scenarios we tested.

We have the Javascript application on H01 server and GP Service on H02 server. So we send request from H01 to H02. Both the machines are in the same domain.

Following tests works fine


Following tests don't


The "H02" server where AGS is installed is managed by their IT department and we don't have much access to it.

In the tests above, I cannot access any URL from "H02" server using proxy, even the root iisstart.htm. They all give Error 500, the page cannot be accessed.

It looks to me like permission or settings on "H02" server that is causing this issue. All the above tests works fine on our internal server.

  • Are you seeing any warnings in your console or anything? Sometimes you can see a specific warning or security issue there. @raykendo is correct in that you need to work with whomever manages the server to make sure things are allowed to be routed the way you need them to be.
    – Branco
    Jun 18 '15 at 12:57

This might be a network firewall issue. If two machines are on the same network, with separate public IP address, and the proxy on one machine makes an outbound call to the second machine's public IP, the firewall may flag that as inappropriate traffic, and block it.

Talk with the system administrator for the network and see if they make an exception to the network policy for your proxy.

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