reportAvOnComRelease MDA
Note
This article is specific to .NET Framework. It doesn't apply to newer implementations of .NET, including .NET 6 and later versions.
The reportAvOnComRelease managed debugging assistant (MDA) is activated when exceptions are thrown due to user reference counting errors while performing COM interop and using the Release or ReleaseComObject method combined with raw COM calls.
Symptoms
Access violations and memory corruption.
Cause
Occasionally, an exception is thrown due to user reference counting errors while performing COM interop and using the Release or ReleaseComObject method combined with raw COM calls. Normally, this exception is discarded because not doing so would cause an access violation in the CLR, bringing it down. When this assistant is enabled, such exceptions can be detected and reported instead of being simply discarded.
Resolution
Examine your reference counting code and search for errors as well as examining the native clients of your object for reference counting errors.
Effect on the Runtime
Two modes are available. If the allowAv attribute is true, the assistant prevents the runtime from discarding the access violation. If allowAv is false, which is the default, the runtime discards the access violation, but a warning message is reported to the user to indicate that an exception was thrown and discarded.
Output
If possible, the output contains the COM interface pointer's original vtable. Otherwise, an informational message is displayed.
Configuration
<mdaConfig>
<assistants>
<reportAvOnComRelease />
</assistants>
</mdaConfig>
