In Windows 3.1, most WNet functions return WN_SUCCESS on success, and unique nonzero values for various error conditions. Applications use the WNetGetError and WNetGetErrorText functions used to obtain network-specific error codes and text messages.
In Windows NT, the WNet functions still return error codes, but applications can call GetLastError and WNetGetLastError to obtain error information. WNetGetError and WNetGetErrorText functions are no longer used.
Windows 95 is very much like Windows NT. Applications can still call GetLastError and WNetGetLastError to obtain error information. A mechanism is also provided for an NP to specify custom error text for standard operations that the NP knows are targeted only to its network. See the function definition for WNetGetLastError for more information.
In general, function calls may return any errors (such as "insufficient memory") even if the error is not specifically mentioned in the API description.