Validation of viewstate MAC failed while running Jmeter script

Question

I have a one script which is running for 1 user. But when I start giving more than 1 user script giving me following error at form filling request. The application is developed using asp.net.

http://go.microsoft.com/fwlink/?LinkID=314055 Source Error:

The source code that generated this unhandled exception can only be shown when compiled in debug mode. To enable this, please follow one of the below steps, then request the URL:
1. Add a "Debug=true" directive at the top of the file that generated the error. Example: <%@ Page Language="C#" Debug="true" %> or:

2) Add the following section to the configuration file of your application:
Note that this second technique will cause all files within a given application to be compiled in debug mode. The first technique will cause only that particular file to be compiled in debug mode. Important: Running applications in debug mode does incur a memory/performance overhead. You should make sure that an application has debugging disabled before deploying into production scenario.

Answer 1

It looks like you're trying to test .NET web application. Mind that most likely you will need to correlate at least 2 parameters:

1. VIEWSTATE
2. EVENTVALIDATION

The error you're getting is due to invalid or missing VIEWSTATE parameter. In order to work it around you need to get __VIEWSTATE hidden field from the previous response and add it as a parameter to the next request.

See ASP.NET Login Testing with JMeter guide for comprehensive information and detailed walkthrough.