An "ERROR_ACCESS_DENIED" error occurs when you try to write to a file that is in a network shared folder

• You are using a client computer that is running Microsoft Windows XP Service Pack 1 (SP1).
• You use the WriteFile function to try to write to a file that is in a network shared folder.
• The shared folder is on a server computer that is running either Microsoft Windows 2000 or Microsoft Windows Server 2003.

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• When you used the CreateFile function to create the file, you specified only the GENERIC_WRITE constant in the dwDesiredAccess parameter.
• Server Message Block (SMB) signing is enabled for communication between the client computer and the server computer.

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• Specify the GENERIC_READ constant and the GENERIC_WRITE constant in the dwDesiredAccess parameter.
• Modify SMB signing.

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Specify the GENERIC_READ constant and the GENERIC_WRITE constant in the dwDesiredAccess parameter

• Replace the ServerName placeholder with the name of a server computer that is running Windows 2000 or Windows Server 2003.
• Replace the FolderName placeholder with the name of a network shared folder on the server computer.

// Specify the GENERIC_READ constant and the GENERIC_WRITE constant
// in the dwDesiredAccess parameter when you create the file.
hFile = CreateFile("\\\\ServerName\\FolderName\\Test.txt", GENERIC_READ |
    GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);

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Modify SMB signing

1. In Registry Editor, locate and then click the following registry subkey:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Lanmanserver\Parameters
2. In the right pane of Registry Editor, right-click requiresecuritysignature in the Name field, and then click Modify. The Edit DWORD Value dialog box appears.
3. In the Value data box, type 0, and then click OK.
4. Quit Registry Editor, and then restart the computer.

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Steps to reproduce the behavior

1. On a computer that is running Windows XP SP1, use Microsoft Visual C++ 6.0 to create a simple Win32 Console Application project that is named Test. By default, the Test.cpp file is created.
2. Create a file by specifying only the GENERIC_WRITE constant in the dwDesiredAccess parameter when you use the CreateFile function.
3. Use the WriteFile function to try to write to the file. To do this, replace the existing code in the Test.cpp file with the following code.
   
   Note Replace the following placeholders:
   • Replace the ServerName placeholder with the name of a server computer that is running Windows 2000 or Windows Server 2003.
   • Replace the FolderName placeholder with the name of a network shared folder on the server computer.
   :

   #include "stdafx.h"
   #include "windows.h"
   #include "stdio.h"
   #include "conio.h"
   
   void main()
   {
       HANDLE hFile;
       char lpBuffer[99999];
       DWORD lpNumberOfBytesWritten;
   
       // Write data to the buffer that you will
       // you use to write data to the file.
       for (int i = 0; i < 100000; ++i)
           lpBuffer[i] = 'a';
   
       // Specify only the GENERIC_WRITE constant in the
       // dwDesiredAccess parameter when you create the file.
       hFile = CreateFile("\\\\ServerName\\FolderName\\Test.txt",
           GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL);
   
       // Try to write the data in the buffer to the file.
       // If the call to the WriteFile function fails,
       // call the GetLastError function.
       if (!WriteFile(hFile, lpBuffer, 100000, &lpNumberOfBytesWritten, NULL))
   
           // If an ERROR_ACCESS_DENIED error has occurred, inform the user.
           if (GetLastError() == ERROR_ACCESS_DENIED)
           {
               printf("An ERROR_ACCESS_DENIED error has occurred.");
               printf("Press any key to continue.");
               getch();
           }
   
       // Close the handle to the file.
       CloseHandle(hFile);
   }

4. Build and then run the application. A console window appears. If the behavior that is mentioned in the "Symptoms" section occurs, the console window contains the following output:
   An ERROR_ACCESS_DENIED error has occurred.
   Press any key to continue.

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