The extension has not been activated

Error Message

When using an extension, ArcMap or ArcCatalog returns the following error:

"The extension has not been activated"

Cause

The referenced extension isn't activated.

Solution or Workaround

1. Start ArcMap or ArcCatalog.
2. Navigate to Tools > Extensions.
3. Check the box next to the desired extensions.
   
   
4. Click Close.