Console Shows Intermittently a Fatal Error Cannot Connect to the Database

Products

• Carbon Black App Control

Issue/Introduction

• App Control Console shows a Fatal Error similar to:

  The Carbon Black App Control Console cannot connect to the database. Ensure that the database server is running.

• PHP_Errors.log file includes references similar to:

  DB Error: [Microsoft][ODBC Driver 17 for SQL Server]TCP Provider: The wait operation timed out.

Environment

• App Control Console: All Supported Versions
• App Control Two Tier Installation
• Microsoft SQL Server: All Supported Versions

Cause

Communication between the ODBC Driver and the SQL Server is failing to properly connect.

Resolution

1. If using "Always On Availability Groups" verify that App Control installation is properly configured for MultiSubnetFailover
2. Verify that "MS SQL Server 2012 Native Client" has not been removed recently by Windows patching in Control Panel > Programs 
3. Test the SQL connection between the two application servers

Additional Information

If the issue persists, continue with Troubleshooting Console Unavailability.