A very specific error that Windows users may encounter is the 'Windows Resource Protection could not start the repair service' error. This particular error message could appear when the 'sfc /scannow' command is used by a malfunctioning System File Checker service to fix a corrupted TrustedInstaller. Before we move forward to the possible solutions, let's take a look at what are these two processes exactly and what their purpose is.
TrustedInstaller is a part of the Windows Modules Installer service and is tasked with enabling the installation, modification and removal of otherwise protected Windows Updates and optional system components. System File Checker (SFC) is a built-in Windows utility that scans for and repairs corrupted files.
Two possible solutions that have a high degree of success in fixing the 'Windows Resource Protection could not start the repair service' error require the use of an elevated Command Prompt. Affected users will have to type 'command prompt' in the Seach field, then right-click the displayed result and select 'Run as administrator.' Now that we have an increased Command Prompt running input the following command - 'sc config trusted installer start=demand' and press Enter. We are not done yet, input the 'net start trusted installer' command and again press Enter. If everything went smoothly, the next time you run the SFC utility, it will not trigger the "Windows Resource Protection could not start the repair service" error.
However, if that is not the case, users might want to try performing a Deployment Image Servicing and Management (DISM) scan. It is a convenient utility capable of repairing errors in Windows Setup, Windows Recovery Environment and Windows images. To run a DISM scan, follow the instructions for opening an elevated Command Prompt. Once it is up and running, input the 'DISM /Online /Cleanup-Image /RestoreHealth' command and press 'Enter.'