You may also need to reinstall the packages, as a corruption there can trigger 0xC1 errors. 3. Check for service path issues
(if file is in use or protected):
: If you are downloading an ISO directly, ensure it is fully verified. Some users found success by re-downloading the file using a different browser to avoid corruption during the transfer. could not load required file winsetup dll 0xc1 verified
Look for any key named setup.exe or winsetup.dll . If present, delete it (these are usually left by debugging or malware shims). You may also need to reinstall the packages,