When you run web tests in Microsoft Visual Studio 2010 or Microsoft Test Manager (MTM), the test controller (QTcontroller.exe), or Visual Studio (Devenv.exe) crashes or stops responding if the test results are too large. Specifically, this issue occurs if the test results (.webtestresults) file is 1.5 gigabytes (GB) or larger. Additionally, an exception occurs and you receive the following error message:

(QTController.exe, PID <n>, Thread <n>) TcmRunner: Unhandled exception for run [90]: Internal Error! 
Failed to acquire a ReaderLock


This issue occurs because a web test runs many iterations and then produces a large web test result file, which takes a long time to be serialized. However, the QTController.exe process is a 32-bit application. The memory space 32-bit applications is limited to only 2 GB.


This hotfix has to be applied on both the controller and the Visual Studio client. Otherwise, the client cannot view the results correctly.

Hotfix information

A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft website: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.


To apply this hotfix, you must have Visual Studio 2010 Service Pack 1 (SP1) installed.

Restart requirement

You may have to restart the computer after you apply this hotfix if the affected files are being used. We recommend that you exit Visual Studio 2010 before you apply this hotfix.

File information

The global version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

File name

File version

File size











For more information about how to install and configure Visual Studio agents, test controllers, and build controllers, visit the following MSDN website:

How to install and configure Visual Studio agents, test controllers, and build controllers


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

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