SQL Server Error: 18456 Severity: 14 State: 12 Connection Error

Unable to Connect to SQL Server Due to Error: 18456, Severity: 14, State: 12

Details:

SQL Server Error: 18456 Severity: 14 State: 12 or Error: 18456, Severity: 14, State: 12 Login failed for user ‘Username’ issue is caused by permissions issue. The following error appears in the SQL Server log:

Login failed for user 'Username'. Reason: Login-based server access validation failed with an infrastructure error. Check for previous errors. [Client: 10.0.0.1]
Error: 18456, Severity: 14, State: 12

Cause:

Error: 18456, Severity: 14, State: 12 means that the authentication is successful to the SQL Server but the server access fails due … Read the rest