Windows update fails to download

Why is my Windows Update giving me this message when I try to install ANY type of update??

Windows Update Error

Windows Update has encountered an error and cannot display the requested page.

Select from any of the following pages for information about Windows Update services, or send us your feedback.

Windows Update Home Page
About Windows Update
Support Information

You can also get online support if you are having problems with Windows Update.

Send error number to Microsoft (0x800A138F)
Note This sends error information but does not create a support incident; you may or may not receive a response.