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