In ArcGIS for Desktop, when attempting to establish a connection to a geodatabase, the following error is returned:
Error: Failed to connect to database. The geodatabase is not accepting connections. Please contact your geodatabase administrator.
The 'Geodatabase is accepting connections' check box is unchecked in the database properties, which prevents new connections to be made to the geodatabase.
Enable the Geodatabase is accepting connections option.
Note: Only a geodatabase administrator can apply the steps provided below.