Explanation: This message may mean the Foxhound database was already running when you tried to start it again; for example, you used the Foxhound2 - Tools - Start Foxhound Engine shortcut when the Foxhound database is already running:

C:\ProgramData\RisingRoad\Foxhound2>ECHO OFF
Start Foxhound Engine
SQL Anywhere Start Server In Background Utility Version 12.0.1.3298
DBSPAWN ERROR:  -81
Invalid database server command line
******************************************************************
*** ERROR ********************************************************
*** dbspawn/dbsrv12 set ERRORLEVEL = 1
09/25 11:47:21. Can't open Message window log file: foxhound2_debug.txt
Press any key to continue . . .

If you want to restart the Foxhound database, try using the Foxhound2 - Tools - Stop Foxhound Engine shortcut first.

With some of the shortcuts, like Foxhound2 - Start Foxhound via Chrome, you can just ignore this message and press a key to contine opening Foxhound in the Chrome browser.

If you are using one of the following "debug" shortcuts to stop and restart the Foxhound engine, try running it again. The previous dbsrv12.exe process may not have had enough time to release the foxhound2_debug.txt file before a new dbsrv12.exe process tried to open that file:

All Programs - Foxhound1 - Tools - Start Foxhound via Chrome - debug

All Programs - Foxhound1 - Tools - Start Foxhound via Firefox - debug

All Programs - Foxhound1 - Tools - Start Foxhound via IE - debug

If the problem persists, Foxhound may already running as a service and the "debug" shortcut may not able to stop the Foxhound database before starting it again. Look for an earlier message "Unable to stop database server -- Request to start/stop database denied."

See also...
Invalid database server command line
Unable to stop database server -- Request to start/stop database denied.