To be consistent with Windows 3.1, the functions continue to return error codes. However, they also set the last error so GetLastError can also be used when the return code is not WN_SUCCESS.
The Windows 3.1 WinNet WN_ xxx error symbols have been retained. However, their values are mapped to the corresponding error in the Win32 error range. The mappings are as follows:
#define WN_ACCESS_DENIED ERROR_ACCESS_DENIED #define WN_ALREADY_CONNECTED ERROR_ALREADY_ASSIGNED #define WN_BAD_HANDLE ERROR_INVALID_HANDLE #define WN_BAD_LOCALNAME ERROR_BAD_DEVICE #define WN_BAD_NETNAME ERROR_BAD_NET_NAME #define WN_BAD_PASSWORD ERROR_INVALID_PASSWORD #define WN_BAD_POINTER ERROR_INVALID_ADDRESS #define WN_BAD_PROFILE ERROR_BAD_PROFILE #define WN_BAD_PROVIDER ERROR_BAD_PROVIDER #define WN_BAD_USER ERROR_BAD_USERNAME #define WN_BAD_VALUE ERROR_INVALID_PARAMETER #define WN_CANCEL ERROR_OPERATION_ABORTED #define WN_CANNOT_OPEN_PROFILE ERROR_CANNOT_OPEN_PROFILE #define WN_CONNECTION_CLOSED ERROR_CONNECTION_UNAVAIL #define WN_DEVICE_ERROR ERROR_GEN_FAILURE #define WN_DEVICE_IN_USE ERROR_DEVICE_IN_USE #define WN_EXTENDED_ERROR ERROR_EXTENDED_ERROR #define WN_FUNCTION_BUSY ERROR_BUSY #define WN_MORE_DATA ERROR_MORE_DATA #define WN_NO_ERROR NO_ERROR #define WN_NO_MORE_ENTRIES ERROR_NO_MORE_ITEMS #define WN_NO_NET_OR_BAD_PATH ERROR_NO_NET_OR_BAD_PATH #define WN_NO_NETWORK ERROR_NO_NETWORK #define WN_NOT_AUTHENTICATED ERROR_NETWORK_ACCESS_DENIED #define WN_NOT_CONNECTED ERROR_NOT_CONNECTED #define WN_NOT_CONTAINER ERROR_NOT_CONTAINER #define WN_NOT_LOGGED_ON ERROR_NOT_LOGGED_ON #define WN_NOT_SUPPORTED ERROR_NOT_SUPPORTED #define WN_OPEN_FILES ERROR_OPEN_FILES #define WN_OUT_OF_MEMORY ERROR_NOT_ENOUGH_MEMORY #define WN_RETRY ERROR_RETRY #define WN_SUCCESS NO_ERROR #define WN_WINDOWS_ERROR ERROR_UNEXP_NET_ERR