Windows update are stuck on downloading or install

Reset Windows update components.

Resetting Windows Update Components will fix corrupt Windows Update Components and help you to install the Windows Updates. Please follow the below steps to reset the Windows Updates Components manually:

Press Windows Key + X on the keyboard and then select “Command Prompt (Admin)” from the menu. Stop the BITS, Cryptographic, MSI Installer and the Windows Update Services. To do this, type the following commands at a command prompt. Press the “ENTER” key after you type each command.

net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver

Now rename the SoftwareDistribution and Catroot2 folder. You can do this by typing the following commands in the Command Prompt. Press the “ENTER” key after you type each command.

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 Catroot2.old

Now, let’s restart the BITS, Cryptographic, MSI Installer and the Windows Update Services. Type the following commands in the Command Prompt for this. Press the ENTER key after you type each command.

net start wuauserv
net start cryptSvc
net start bits
net start msiserver

Type Exit in the Command Prompt to close it.

Now you may try running the Windows Updates and check if the above steps resolve the issue.

For reference: https://support.microsoft.com/en-us/kb/971058

Optionally if update still gets stuck, you can do all steps until start,
you can download the updates from Microsoft Catalog and update manually. Search for relevant KB in the Catalog.

Microsoft Catalog - https://www.catalog.update.microsoft.com/Home.aspx