Running instrumented applications result in "compatibility mode is not supported"

Technote (troubleshooting)


Attempts to run an application with IBM Rational PurifyPlus for Windows result in the error "compatibility mode is not supported".


The following is the full error message.

PURE: Your application is running in compatibility mode. (Environment variable: __COMPAT_LAYER; value: VistaSetup) Running in compatibility mode is not supported and may cause the application not to run properly. If you experience problems, either change the compatibility mode setting or use Selective Instrumentation.


This error will occur if the __COMPAT_LAYER environment variable is set while running an instrumented application. Rational PurifyPlus does not support testing an application that is running in compatibility mode.

Diagnosing the problem

Rational PurifyPlus will not set the __COMPAT_LAYER environment variable on it's own.

Run the command "set" at a DOS prompt to determine if the __COMPAT_LAYER variable is set in the environment. If it's not listed, the OS is likely setting the Compatibility Mode flag on the instrumented executable.

Resolving the problem

To resolve the problem, the __COMPAT_LAYER environment variable must be unset in the environment.

If this variable is not set in the environment, perform the following steps to ensure that the executable is not set to run in compatibility mode.

  1. Right-click the instrumented .exe in the Rational PurifyPlus cache directory. By default the cache directory is [[code srctext="codesnippet">]C:\Progam Files\IBM\RationalPurifyPlus\PurifyPlus\cache

  2. Select Properties

  3. Click the Compatibility tab

  4. Ensure that the option Run This Program In Compatibility Mode For: is not selected.

Cross reference information
Segment Product Component Platform Version Edition
Software Development Rational Purify Runtime Windows 7.0.1
Software Development Rational PureCoverage Runtime Windows 7.0.1
Software Development Rational Quantify Runtime Windows 7.0.1

Document information

More support for:

Rational PurifyPlus family

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