Microsoft KB Archive/124877

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PRB: Error 6 RPC_S_PROTSEQ_NOT_SUPPORTED in 16-bit Application


The information in this article applies to:

  • Microsoft Windows Software Development Kit (SDK) 3.1


When trying to run a 16-bit RPC application, the RpcBindingFromStringBinding() may return error number 6. In the RPCERR.H file, this is defined as:



Unlike Windows NT, the 16-bit environments do not automatically install the RPC runtime files and drivers. If the driver for the protocol sequence your are using is not installed, or is not in your path, RpcBindingFromStringBinding() will fail with error code 6.


The 16-bit RPC runtimes and drivers ship with the Win32 SDK. You can install them from the CD by going to the \mstools\rpc_dos\disk1 directory on the CD and running setup. By default, the installation should install all drivers. If you want to verify that, choose the custom install option.

After the drivers are installed, you will need to make sure that they are in your path before attempting to run a 16-bit RPC application.

NOTE: You must install the 16-bit drivers even if you are running your 16-bit application on a Windows NT host.


Windows drivers have the extension .DLL and DOS drivers have the extension .RPC. The driver names and the protocol sequence they support are as follows:

   rpc16c1    - Named Pipes
   rpc16c3    - TCP/IP
   rpc16dg3   - UDP/IP
   rpc16c4    - DEC Net
   rpc16c5    - NetBIOS
   rpc16c6    - SPX
   rpc16dg6   - IPX 


The "Installing RPC" section of the RPC Programmer's Reference.

Additional query words:

Keywords : kberrmsg kbnetwork kb16bitonly kbAPI kbRPC kbSDKPlatform kbOSWin310 kbGrpDSNet
Issue type : kbprb
Technology : kbAudDeveloper kbWin3xSearch kbSDKSearch kbWinSDKSearch kbWinSDK310

Last Reviewed: November 5, 1999
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