Common problems brought to me, in the order of frequency, in regards to update issues on a secured (as it is shipped by Microsoft) Windows - applies to Vista and later :

Firewalls, proxies or other security tools are blocking.

In particular free 3rd party products (non-Microsoft) are often over sensitive and tend to block access to the internet for any application.

The application was copied to another folder, or from another computer.

If files or folder structures were modified updates may fail. For example, if an attempt was made to copy an installation to i.e. C:\MyFolder Windows User Access Control will deny access to modify any files within this folder and its sub-folders.

The application was installed with another user account or with elevated privileges.

The same Windows user account who installed the application can run, update and uninstall the application - Windows User Access Control. It will fail for any other Windows users, unless Windows default security has been compromised. If Windows UAC settings have been changed, applications installed into any other than the intended folder, the user-space, may fail. On a secured Windows when executing the installer or any part of the application using "Run as Administrator" or "Run as..." settings also will cause access issues.

Internet Explorer is set Offline.

The Windows HTTP API shares it's basic settings with Internet Explorer. Even you don't use IE, set it Online.

The update server is temporarily unavailable.

In case the updater or the application itself tells that the connection can not be established, check your internet connection and try later.

The previous version is too old.

Automatic updates of versions and builds prior to March 2014 are not available.

Never accept an update or any other modification of your installation, even an online friend offers it!
In any case, uninstall the previous version, download the recent version, install it and best is not to modify any part of the application.