What should I do if the Win10 upgrade fails? What should I do if the Win10 upgrade encounters a 0x80070002 error?

                                                                                                                                                                                         After the official release of Win10, many Win8.1 users in the process of upgrading Win10 official version, the installation directly restarted encountered 0x80070002 error, and the upgrade will fail after the error, and automatically fall back to Windows 8.1 system. What should I do if the Win10 upgrade fails? Win10 upgrade encounters 0x80070002 error how to do? Anxia Xiaobian will analyze the problem, I hope to help everyone.
Cause 1: Joining other hard drives causes the primary partition to identify problems.
The root of the Microsoft community, an insider revealed that if the computer
used HDD mechanical hard disk as the main hard disk, but later added and enabled the second hard disk, for example, upgrade to SSD The hard disk may cause the Win10 installer to recognize the current partition information error, which may cause the installation to fail.
The solution is as follows:
Remove the old main hard disk and re-partition format, avoid the Win10 installation program is not stupid, or remove the old disk before the upgrade, and then plug it in.
Cause 2: Non-Microsoft Service Interference
The startup of non-Microsoft services may cause interference to the Win10 installer, you can disable it first.
The solution is as follows:
Enter MSConfig in the run, enter the system configuration after the carriage return, and then find the service. First click on the bottom left corner to hide all Microsoft services, disable all others first, and then install Win10 and then enable it as appropriate. .

Cause 3: Killing soft monitoring interference
Third-party anti-virus software and security software may also hinder the normal operation of the installation program. To be safe, you must disable all real-time killing before upgrading Win10. The monitoring program even needs to temporarily uninstall the software to ensure that the Win10 upgrade is successful, and then re-install it once.