Windows 1903 encountered an error.
Windows 1903 encountered an error.
Windows 1803 won't progress past version 1903. It installs but crashes at step 100 with error 0xc1420121. Attempts like restarting, using Windows Update Assistant, and DISM checks didn't resolve the issue—restore health failed and source files appear corrupted. Likely a file corruption problem that could block the update. TLDR: The failure stems from potential image corruption affecting the update process.
Check your Windows update assistance here: https://www.microsoft.com/en-gb/software.../windows10
It's likely that a failing corrupt system might lead to an update not completing. Consider executing sfc /SCANNOW with elevated privileges.
The SFC confirmed that Windows Resource Protection detected no integrity breaches.
Microsoft keeps ISO files from previous Windows releases. Download 1803 in your preferred language and architecture, then mount the ISO. After that, attempt the DISM restore health command once more, this time applying the /source switch with <virtual DVD>:\Source\install.esd (or .wim) as the source.