Most likely your PC can't connect to the database due to network and/or a PC startup issue. If you restart your PC (restart your server first if you have a network server). This should resolve the problem.
Error 6420 is an Advantage database communication error. "6420 Unable to "discover" the Advantage Database Server.
Try the following
Close your client PC(s), restart your server PC, then start your client PC
If the above doesn't work ask your IT technician to check one or more of the following:
- Your wireless network is connected and working
- Your wired network is connected and working
- Your Transactor Desktop shortcut is correctly configured to connect to the live database location