Troubleshooting Web Tests
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Troubleshooting Web Tests

This topic lists the following common issues that occur when you work with Web tests in Visual Studio Team Edition for Testers.

The Remote Name Could Not Be Resolved

JavaScript and ActiveX Controls Do Not Run

Coded Web Test Error Caused by Unbound Data Source

If your Web test contains external URLs that are outside your firewall, you might receive the following error message when you run your test:

RequestFailed: The following error occurred which may indicate you need to configure a proxy server in your Web test: The remote name could not be resolved.

If you use a proxy server to access Web sites outside your firewall, you must manually set the proxy property on the Web test to the proxy server that your browser uses to view Web pages. Set the proxy by using the Web Test Editor.

To specify a proxy server

  1. Open a Web test.

  2. In the request tree, select the root node. The root node will be the name of the Web test.

  3. In the Properties window, locate the Proxy property and type a valid proxy name. Ask your network administrator for a valid proxy name, or type "default" to use Internet Explorer's proxy settings.

    Caution noteCaution

    Using "default" as your proxy setting can cause performance problems when you run your Web test under load. It is better to specify a proxy other than "default" when you run your Web test in a load test.

Web sites that use script or ActiveX controls might display this error message:

Your security settings do not allow Web sites to use ActiveX controls installed on your computer. This page may not display correctly...

The Web test viewer does not allow script or ActiveX controls to run, because the Web test engine does not run them. This message indicates that a real browser would potentially display some additional dynamic content in the page. Typically, no user action is required in response to this message. For more information, see About JavaScript and ActiveX Controls in Web Tests.

While you are trying to run a coded Web test, you might see the following error message:

Could not run test <Test Name> on agent <Computer Name>: Object reference not set to an instance of an object.

This can occur because you have a DataSourceAttribute defined for the Web test class, without a corresponding DataBindingAttribute. To resolve this error, add an appropriate DataBindingAttribute. Alternatively, if you do not need the DataSourceAttribute delete it or comment it out of the code.


An unbound data source is only one possible cause of the error Object reference not set to an instance of an object. There are other possible causes of this error, including problems in the code of the Web test itself. You must also check the code of your Web test when you see this error.

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