If you are able to connect to your SQL server using Window Authentication mode, but encountered error when connect using SQL Server Authentication mode, Most probably, you need to turn on Server Properties:

If you still encounter the issue after turn on “SQL Server & Window Authentication Mode”, you may need to check the detail error log for more information.

  1. Click on the Technique Detail button when the error message prompted.

2) Check the State number.

3) Here is some of the reasons of fail to connect to SQL Server: