The functions for starting a stopping SQL server and for connecting clients returns a value from the table below.
| Constant | Number | Error description |
| KSE_OK | 0 | No error |
| KSE_WINDOWS | 1 | Cannot open server window |
| KSE_FAKE_SERVER | 2 | Unauthorized 602SQL Server - identity check failed. |
| KSE_ENCRYPTION_FAILURE | 3 | Encryption failure - the client and server use different encryption methods |
| KSE_WINEXEC | 4 | Client could not start the local 602SQL Server. On Linux happens if xterm not installed. |
| KSE_NO_MEMORY | 5 | Memory allocation error |
| KSE_NO_FIL | 7 | Server cannot run, the name is not registered |
| KSE_DAMAGED | 8 | Database file is damaged |
| KSE_SYSTEM_CHARSET | 9 | The operating system doesn't support the system language of the database server |
| KSE_SERVER_CLOSED | 10 | Server access temporarily disabled |
| KSE_BAD_VERSION | 11 | Database file version is different from the server version |
| KSE_NETWORK_INIT | 12 | Cannot initialize the specified network protocol |
| KSE_CLIENT_SERVER_INCOMP | 13 | Server version not compatible with client version |
| KSE_NOSERVER | 14 | Server not found on network, invalid IP address specified |
| KSE_CONNECTION | 15 | Cannot establish connection with the 602SQL Server |
| KSE_NOTASK | 16 | Maximum number of concurrent client connections has been exceeded |
| KSE_UNSPEC | 17 | Internal connection error |
| KSE_NO_NETWORK_LICENCE | 18 | SQL server doesn't have a licence for network access |
| KSE_NO_HTTP_TUNNEL | 19 | HTTP tunneling not started on the server or there is Web XML interface on the same port |
| KSE_DBASE_OPEN | 23 | Another server is already connected the database or your have insufficient privileges to the database file |
| KSE_SERVER_NAME_USED | 24 | A database server with the same name is already running on the network |
| KSE_START_THREAD | 25 | Cannot run another thread on the server |
| KSE_SYNCHRO_OBJ | 26 | Cannot create synchronization object |
| KSE_MAPPING | 27 | Cannot map memory file |
| KSE_TIMEOUT | 29 | Response timeout to local server |
| KSE_NO_WINSOCK | 30 | TCP/IP socket library is not working |
| KSE_WINSOCK_ERROR | 31 | Error working with a socket |
| KSE_FWNOTFOUND | 35 | SOCKS server not found |
| KSE_FWCOMM | 36 | Error communicating with SOCKS server |
| KSE_FWDENIED | 37 | SOCKS server refused to establish the connection with the 602SQL Server |
| KSE_BAD_PASSWORD | 38 | Incorrect database file password specified |
| KSE_ESCAPED | 39 | Server stopped at the password dialog for encrypted access |
| KSE_CANNOT_CREATE_FIL | 42 | Server cannot create the database file |
| KSE_CANNOT_OPEN_FIL | 43 | Server cannot open the database file |
| KSE_CANNOT_OPEN_TRANS | 44 | Server cannot open the transaction file |
| KSE_IP_FILTER | 45 | Access from this IP address is denied, IP filter set |
| KSE_INST_KEY | 47 | Missing or invalid Product ID |
| KSE_NO_SERVER_LICENCE | 48 | 602SQL Server is not licensed |
These error numbers may be reported in all client interfaces, if they fail to connect to the server.
