Symptoms

The following error message appears during the processing:

EngineLoader: System.AccessViolationException: Attempted to read or write protected memory.

Cause

Using the default Engine Loader, provided with the standard C# code samples, in the EngineLoader.Dispose() method the line:

hresult = dllCanUnloadNow(); 

returns hresult = 1, so the FREngine.dll is not free.

This causes the following error

“System.AccessViolationException: Attempted to read or write protected memory”

, when the initializeEngine function is called in another process.

Resolution

Change the code of the EngineLoader.Dispose() in this way:

engine = null;
//int hresult = deinitializeEngine(); //delete it

// Deleting all objects before FreeLibrary call
GC.Collect();
GC.WaitForPendingFinalizers();
GC.Collect();
int hresult = deinitializeEngine(); //put it here   
hresult = dllCanUnloadNow();