Recently I was working on performance testing for one of my application and came across this issue where all of my call failing in JMeter.
I started analyzing and found it was a wizard where series of calls were on same page using ASYNC Ajax calls which were complaining “The page is performing an async postback but the ScriptManager.SupportsPartialRendering property is set to false. Ensure that the property is set to true during an async postback” due to which my main POST was failing with error “Invalid postback or callback argument”.
The strange thing was all of this was working fine when run via UI. Then started reading about when this error occurs and came across one discussion on a forum where they mentioned about SupportsPartialRendering is not supported by every browser.
I noticed that I used Firefox to record and i was testing UI on Chrome.
So as a solution i updated the user-agent string for my JMeter HTTP Samplers and that did the trick 🙂
This was happening because – ASP.NET2.0 have a feature added for Event validation – Event validation checks the incoming POST request to ensure that the event causing the Postback / callback is valid and the event which triggered the Postback /callback is expected by the Runtime. If the runtime finds a Postback / callback by an event which is not registered for validation, it throws an exception. Event validation can help prevent injection attacks from malicious users who are trying to POST data by an event which does not come up from the controls registered to the page.