Lenovo P71 Windows 10 Pro Upgrade from 20H2 to 21H1 fails with Intel RST: The inbox storage driver iastora.sys doesn't work on these systems

Solution 1:

You can do 3 things with this driver:

All are referenced here:

Intel RST

Solution One – Reset the Startup Intel® RST Service. Find this in Services.

Solution Two – Update the Intel® RST driver. Either in Device Manager or via Lenovo System Update / Vantage. You can also look in the Intel Download Centre for your specific model of laptop.

Three: Uninstall the Driver. Select Device Manager. Find and expand the Disk drives catalog. Right-click on Intel® Rapid Storage Technology and choose Uninstall device.

If none of the above (specifically 3 - uninstall) work, you may need to try a Window 10 Repair Install from the Microsoft Media Creation Link.

https://www.microsoft.com/en-us/software-download/windows10