It did not work for me. Laptop (No. 1 PC maker) came with pre-installed W8.1 x64 Home. On the last day of W10 free-upgrade program of 2016, got a digital entitlement. Moved to 10 Home since 2018. Recently think of moving to W10 pro. Since the laptop does not support W7: Clean installed into W8.1 pro (with ei.cfg and PID.txt. SSD has been reformatted since 2018). Installed all the drivers. Applied MKT (KMS). Disconnect from internet. Upgraded to 10 from setup.exe (with ei.cfg and PID= xxx-3VV6T). Installed all the drivers again. Connect to internet. 0x803F7001. Tried three 1511 iso, including the one multi edition OEMRET from this thread. One thing I'm not sure is W8.1 pro iso. Version check on install.wim shows: Version : 6.3.9600 ServicePack Build : 17415 Don't know which steps I have done wrong. Please help!