For error codes you may mean:
- Exit codes of WinSCP executables;
- Error codes of specific protocol you are using with WinSCP.
The SFTP and FTP protocols have standard set of error codes. The server should provide human readable description of the error along with the code, particularly for generic classes of error codes. In the error messages, WinSCP include both the error code and human readable description.
You can refer to standard set of error codes in the protocol specifications: