mPulse is designed to capture as much real visitor data as possible. Synthetic monitoring services are not real customers, running the same transaction or accessing the same page on a scheduled basis. As a result, this could skew both traffic and performance statistics.
To prevent this, mPulse detects most synthetic monitoring service using the user-agent string, and returns a 204/No Content response when the config.js (the customer-specific mPulse configuration JSON) is requested from the mPulse network. In the example below, the request is originating from a host identifying itself as a Compuware/Gomez Synthetic Agent. In response, the mPulse System returns a 204/No Content.
This is not an error, but a design feature of the mPulse system.