How to resolve "Access denied. You do not have permission to access this content” in SharePoint 2010
In this article we will be seeing how to resolve "Access denied. You do not have permission to access this content" in SharePoint 2010 external data picker when you are trying to access the external data. When you create External data column in SharePoint 2010 list you would be specifying the External content type that you have created, you need to set the permissions in "Business Data Connectivity service application" for the external content type. If you do not set the permissions for your external content type and if you try to use that to access external data it will throw you an error as shown below.
Go to Central Administration -> Application Management -> Manage Service Applications.
Click on Business Data Connectivity Service.
In the top Ribbon click on Manage.
In Service Application Information check the corresponding External Content Type that you have used for creating the external list.
And in the top Ribbon click the Site Object Permissions.
Site Object Permissions wizard will pop up add the account (Group or Users) and assign the permissions.
Once you have configured Business Data Connectivity access rights navigate to the site and add an item to the External data column.