PRB: Ccdist.exe Fails to Register Comcat.dll Until Reboot (163958)

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Component Categories help identify areas of functionality that an OLE component may support. Applications or components that take advantage of this functionality may redistribute the self-extracting executable, Ccdist.exe, from the Win32 SDK. Ccdist.exe then installs the necessary component categories DLL, Comcat.dll.

Typically, when a redistributable file is distributed as a self-extracting executable, it copies the files to the designated directory in the system and makes the appropriate registry entries. The problem with Ccdist.exe is that it installs Comcat.dll into the system, but fails to register it, until the user reboots the machine. This is due to a limitation in the tool Microsoft used to create the self-extracting Ccdist.exe, where registration happens only on reboot.

Before a component can call any of the ICatRegister functions to register and unregister component category information in the registry, it must first instantiate the component category manager by calling CoCreateInstance (CLSID_StdComponentCategoriesMgr,...). This CoCreateInstance() call fails because although the Comcat.dll is present in the system, it was not registered correctly.

The workaround is to either reboot after installing the DLL, or to call "RegSvr32 ComCat.DLL" after running Ccdist.exe.