Windows 8.1 Update Error 80070026

Run the DISM tool

A.- Swipe in from the right edge of the screen, and then tap Səarch.
(If you're using a mouse, point to the upper-right corner of the screen, move the mouse pointer down, and then click Səarch.)

B.- Enter command prompt in the səarch box.

C.- In the list of results, swipe down on or right-click Command Prompt, and then tap or click Run as administrator.

D.- In the Administrator: Command Prompt window, type the following commands. Press the Enter key after əach command:
DISM.exe /Online /Cleanup-image /Scanhealth
DISM.exe /Online /Cleanup-image /Restorehealth

E.- To close the Administrator: Command Prompt window, type exit , and then press Enter.

F.- Run Windows Update again.

If you still have trouble,

There could be various reasons for which system is not able to repair.

We need to check the policies and registry settings and exceptions and firewall settings and other kind of settings.

For a quick solution seek an expert's help from the following chat link

If the issue is still not fixed, it can be a very critical problem with your computer affecting your personal data and the Windows Operating System. You will have to chat with our Experts or you can check with your local technician to get the problems fixed with very high priority..