Have you been stuck with an error that says ‘Windows failed to load because a critical system driver is missing or corrupt’ with a reference to a driver file iastor.sys while upgrading Windows Vista to Windows 7? This error, which has a status code 0xc0000359 now has a fix from Microsoft.
After throwing up the error with a message which includes the driver file path $windows.~btwindowssystem32driversiastor.sys, the upgrade process is stalled and your system rolls back to Windows Vista. The cause of this issue is an incorrect version of the iastor.sys file on your PC.
How To Fix Windows Vista To Windows 7 Upgrade Error 0xc0000359?
Here are the steps to fix this issue.
1. Go to the folder FileRepository on your C: drive. The path is
2. Search for the file named ‘iastor.inf’. Select all folders which contain this file and move them to a temporary location. Since these are system folders, you may need to take over ownership of the folder and grant necessary file/folder permissions for moving them around.
3. Now find any references to ‘iastor’ in the c:windowsinf folder which has all oem inf files.
You can use regular Windows text search or use the command line.
findstr /i /c:”iastor” %windir%/inf/
4. In the resulting search list, look for any .inf and .pnf files which are named in the form of ‘oem##.inf’ or ‘oem##.pnf ‘where ## is a numeric.
5. Move all such files from the c:windowsinf folder to a temporary location.
6. Delete $~bt, $~LS and $~Upgrade folders from c: drive if they exist.
7. Download the latest version of the iastor.sys driver file from Intel website.
8. Now Start the Windows Vista to Windows 7 upgrade process. This time it should complete successfully.
9. Once the upgrade is done, you need to restore the iastore files, the oem##.inf files and the oem##.pnf files that you have moved in steps 2 and 4 back to their original locations.