You would get this error after configuring a list which uses External Content Type (created using SharePoint Designer or VS 2010). Now you must be wondering when ECT and the list is created with the same login id, why should one get access denied error.
When you create a new list which uses the ECT, it gives Access Denied error
But there is one more step before you use the ECT in a list. In Business Data Connectivity Service in Central Administration we need to set object permission for the ECT.
1. Open CA, navigate to click on ‘Manage Service Applications’ under ‘Application Management’.
2. Click on ‘Business Data Connectivity Service’
3. Select the ECT you are looking for
4. Click on ‘Set Object Permissions’ on the ribbon,
In BDC service application, select the ECT and click on 'Set Object Permissions' in the ribbon
5. Enter the user name you want to give permission to, Click on Add
6. Select permissions for the selected user and click OK.
In the set object permissions popup, add the user and set permissions
That’s it, now go and refresh your list…