I had a similar issue, the workaround I found was removing all spaces , hopefully may be helpful (may work for some)
I changed my connection string
Data Source=ABCD;User ID=USERNAME;Password=PASSWIORDHERE;Initial Catalog=DBNAMEHERE;Provider=SQLNCLI11;
SERVER=ABCD;UID=USERNAME;Password=PASSWIORDHERE;DATABASE=DBNAMEHERE;Provider=SQLNCLI11;
Worked...