If some software in your windows OS wants ext-ms-win-ntuser-windowclass-l1-1-0.dll your operating system will ask for DLL file. When that DLL file is not available you will get this error.
If you have moved your file or changed the name of dll file you will get this error.
You will mostly see there errors when you dll file is missing:
ext-ms-win-ntuser-windowclass-l1-1-0.dll not found
This application failed to start because ext-ms-win-ntuser-windowclass-l1-1-0.dll was not found. Re-installing the application may fix this problem.
There was a problem opening ext-ms-win-ntuser-windowclass-l1-1-0.dll.
Windows failed to start the software because this ext-ms-win-ntuser-windowclass-l1-1-0.dll is missing.
ext-ms-win-ntuser-windowclass-l1-1-0.dll can not be started.
File execution can not start ext-ms-win-ntuser-windowclass-l1-1-0.dll not found.
How To Fix ext-ms-win-ntuser-windowclass-l1-1-0.dll error?
Reinstall the program that asked the ext-ms-win-ntuser-windowclass-l1-1-0.dll.
Update your application to new version.
Update your windows OS.
ext-ms-win-ntuser-windowclass-l1-1-0.dll Download and install in your windows.
Registry clear and optimize Windows OS.
If you need ext-ms-win-ntuser-windowclass-l1-1-0.dll Download it right now and install it into your system to fix the error as soon as possible. just Install ext-ms-win-ntuser-windowclass-l1-1-0.dll and fix your error.