In Microsoft Windows Operating Systems, regsvr32 is a command-line utility used for registering and un-registering OLE controls like DLLs and ActiveX controls in the Windows Registry. For example – a DDL, to be used with regsvr32, must export the functions DllRegisterServer and DllUnregisterServer. This tool may require troubleshooting some problems in Windows or other programs.

Regsvr32 in Windows 11/10

Regsvr32.exe is included in Microsoft Windows and is either installed in the System32 (Windows NT/Windows XP/Windows Vista/Windows 7/Windows 8.1/Windows 10/Windows 11) folder.

Regsvr32 Command and Usage

1. RegSvr32.exe command-line options:

Regsvr32 [/ u] [/ n] [/ i [: cmdline]] dllname

2. Parameters:

/u : It will unregister the file.
/s : Runs regsvr32 silently and does not display any message boxes.
/n : doesn’t call DllRegisterServer. This option should be used with /i.
/i :cmdline : It calls DllInstall passing it an optional [cmdline]. When used with /u, it calls dll uninstall.
dllname: Specifies the name of the dll file that will be registered.
/n – Do not call DllRegisterServer or DllUnregisterServer; this option must be used with /i.

For example, to manually register and unregister a DLL file shm.dll, we can do the following in CMD:

regsvr32 shm.dll for registering a file.
regsvr32 /u shm.dll for uninstalling a file.

Regsvr32.exe Error Messages

The following list contains RegSvr32 error messages and possible causes:

The command-flag “”%1″” is not valid. Please review the command usage and try again.
This command is only valid if a Microsoft Visual Studio OLE Custom Control project is opened.
To register a module, you must provide a binary name.
The command OleInitialize failed to run. Your computer might be low on memory. Close any open programs and then try again.
The module “”%1″” failed to load.\n\n Make sure the binary is stored at the specified path or debug it to check for problems with the binary or dependent .DLL files.\n\n%2.
The module “”%1″” was loaded but the entry-point %2 was not found.\n\nMake sure that “”%1″” is a valid DLL or OCX file and then try again.
The module “”%1″” was loaded but the call to %2 failed with error code %3.\n\nFor more information about this problem, search online using the error code as a search term.
The module “”%1″” may not compatible with the version of Windows that you’re running. Check if the module is compatible with an x86 (32-bit) or x64 (64-bit) version of regsvr32.exe.

On Windows 64-bit version you will find two versions of Regsv32.exe viz. the 64-bit version is in %systemroot%\System32\regsvr32.exe and the 32-bit version is in %systemroot%\SysWoW64\regsvr32.exe explains KB249873.