.load, .loadby (Load Extension DLL)

The .load and .loadby commands load a new extension DLL into the debugger.

.load DLLName  
.loadby DLLName ModuleName


Specifies the debugger extension DLL to load. If you use the .load command, DLLName should include the full path. If you use the .loadby command, DLLName should include only the file name.

Specifies the module name of a module that is located in the same directory as the extension DLL that DLLName specifies.



User mode, kernel mode


Live, crash dump



Additional Information

For more information about how to load, unload, and control extensions, see Loading Debugger Extension DLLs.


When you use the .load command, you must specify the full path.

When you use the .loadby command, you do not specify the path. Instead, the debugger finds the module that the ModuleName parameter specifies, determines the path of that module, and then uses that path when the debugger loads the extension DLL. If the debugger cannot find the module or if it cannot find the extension DLL, you receive an error message that specifies the problem. There does not have to be any relationship between the specified module and the extension DLL. Using the .loadby command is therefore simply a way to avoid typing a long path.

After the .load or .loadby command has been completed, you can access the commands that are stored in the loaded extension.

To load an extension DLL, you can do one of the following:

  • Use the .load or .loadby command.

  • Execute an extension by issuing the full !DLLName.ExtensionCommand syntax. If the debugger has not yet loaded DLLName.dll, it loads the DLL at this point if it is located in the current DLL search path.

Use the .chain command to display information about what has been loaded and the current DLL search path.

0:000> .chain
Extension DLL search Path:
    C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\WINXP;C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\winext;C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\winext\arcade;C:\Program Files (x86)\Windows Kits\10\Debuggers\x64\pri;C:\Program Files (x86)\Windows Kits\10\Debuggers\x64;
Extension DLL chain:
    C:\Windows\Microsoft.NET\Framework64\v4.0.30319\SOS.dll: image 4.8.4084.0, API 1.0.0, built Sun Nov 24 00:38:52 2019

For example, the managed code SOS.dll is not in search path for DLLs shown above, so use the .load command with a complete path to load that dll.

0:000> .load C:\Windows\Microsoft.NET\Framework64\v4.0.30319\SOS.dll