Issue
It is possible to receive the following error while creating a Managed Metadata column for your SharePoint 2010 and SharePoint 2013 site.
This error occurs when selecting the following setting
You will receive an additional error beneath the tekst box area when clicking on OK
The term store could not be accessed.
Solution
Microsoft mentions the below configuration on http://technet.microsoft.com/en-us/library/ee530391(v=office.14).aspx at ‘Update a managed metadata service connection’.
Select the Managed Metadata Service Application Connection
and click on Properties
make sure the second checkbox is checked, ‘’This service application is the default storage location for column specific term sets”, and click on OK
It is now possible to select a Managed Metadata Column and create a custom term set.