regsvr32exe

regsvr32.exe is a Windows command-line utility used to register and unregister COM components, typically DLL or OCX files. When run with a DLL, it loads the library and calls the DllRegisterServer export to install the component, creating the necessary registry entries; with the /u option, it calls DllUnregisterServer to remove them. It is commonly used by software installers and system administrators to enable COM components for applications that rely on them.

Location and architecture: The tool is included with Windows and exists in system directories that reflect the system’s bitness. On 64-bit Windows, regsvr32.exe in System32 is 64-bit, while a 32-bit version exists in SysWOW64. To register a 32-bit DLL on a 64-bit system, use the SysWOW64 regsvr32; to register a 64-bit DLL, use the System32 regsvr32, or specify the full path to the appropriate executable.

Usage: regsvr32 [options] dllname. The most common options are /u to unregister and /s to run silently without a UI. The /i[:cmdline] option passes an optional command line to DllRegisterServer (or DllUnregisterServer when used with /u). Example usages include regsvr32 "C:\Path\MyComponent.dll" to register, regsvr32 /u "C:\Path\MyComponent.dll" to unregister, and regsvr32 /s "C:\Path\MyComponent.dll" for a silent operation. For components that require additional parameters during registration, use the /i option as appropriate.

Administrative considerations: Registering or unregistering COM components typically requires elevated privileges; run regsvr32 from an administrator Command Prompt or PowerShell. Some DLLs have dependencies or require specific bitness, and incorrect usage or mismatched versions can fail to register.