Window 11 upgrade has failed error code 0x8007007f

When encountering error code 0x8007007f during an upgrade from Windows 10 22H2 to Windows 11 using the Installation Assistant, an often-overlooked factor may be whether the device is running on battery power. In one case, the upgrade consistently failed on two identical laptops that were not connected to an external power source. After connecting one of them, the upgrade succeeded without any other changes, while the other continued to fail.

This behaviour suggests the upgrade process may depend on AC power being available — possibly due to safeguards that prevent certain operations while on battery. While many guides recommend steps such as running SFC, DISM, updating drivers, or disabling antivirus software, confirming the device is connected to an external power source should be one of the first checks. It’s simple, quick, and in some cases, sufficient on its own. This small but important step can help avoid unnecessary and time-consuming diagnostics.