Anyone getting this error message:
CAN'T OPEN INSTANCE: sde:sqlserver.
Spatial Engine Connection Failed (-409).
Cannot Get Access to Instance sde:sqlserver
DATABASE RECONNECT: Failed to find hdbc. ERROR in obtaining connection id.
Error: -409: DBMS error code: 8003
[Microsoft][ODBC Driver Manager] Connection not open
Couldn't initialize shared memory, error = -409.
] Cannot Attach to Shared Memory -1
Here's a thread from 2013: https://community.esri.com/thread/75033
What version of ArcGIS Server and SQL Server are running? Can you connect to the instance with SQL Server Management Studio? I wonder if the instance isn't running.....