Known SFTP Server Issues

In this article, you will find known issues categorized by server name and ID.

WS_FTP

ServerID: WS_FTP-SSH_x.x.x FIPS

Symptom:

When a user attempts to copy a file from such server, the following message appears: "Destination Folder Access Denied" and, if the user clicks the "Continue" button, the following error box is displayed "Can't read from the source file or disk".

Reason:

The server reports errors with invalid error code and with non-standard data in its description. This happens when one attempts to read data from a file opened for reading+writing. If a file is opened for reading only, the data could be read successfully. SFTP Net Drive always opens files on servers for reading+writing. Each file on a server is opened only once. Even if different local programs open the same file at the same moment, the file on the server is opened only once with maximum access mode.

Solution:

Servers that use WS_FTP software are supported in read-only mode.

ServerID: WS_FTP-SSH_x.x.x FIPS

Symptom:

When a user attempts to copy a file to such server, the following message appears: "An unexpected error is keeping you from copying the file... Error 0x80070032: The request is not supported".

Reason:

The server does not support file resizing. Windows copies new files to a drive in the following way:

1. Creates the target file
2. Sets file allocation size to the required value (this operation is not applicable because this server supports only SFTP version 4, so this operation is ignored)
3. Sets file size to the required value (this operation is not supported by this server)
4. Sets file size to the required value (this operation is not supported by this server)

If one attempts to copy a file which already exists on the drive, the operational sequence differs a bit - between steps 1 and 2 Windows performs file truncation, i.e. it performs the same operation as on step 3 but with size set to zero.

So because the server does not support file resizing, SFTP Net Drive reports this problem to Windows, and Windows shows the mentioned messages and interrupts file copying.

Solution:

No solution found. Drives for servers with WS_FTP software installed are forcibly mounted as read-only.

Paramiko

ServerID: paramiko_x.x.x.x

Symptom:

When a user attempts to copy a new file to the drive mapped to such server, "Could not find this item" error is displayed.

Reason:

The server creates a file successfully but then reports "File not found" error on each file information request, even when the file is closed successfully.

Solution:

No solution found. Drives for servers with Paramiko software installed are forcibly mounted as read-only.

ServerID: paramiko_x.x.x.x

Symptom:

When a user attempts to overwrite an already existing file, the copy process works forever until the drive is disconnected.

Reason:

When one attempts to overwrite an already existing file, Windows opens the file for writing and then performs file reallocation with new size set to 0 and file truncation. For both last operations the server reports "Unsupported operation" error. SFTP Net Drive reports ERROR_UNSUPPORTED_OPERATION to Windows but it closes the file and performs the same operations again and again.

Solution:

No solution found. Drives for servers with Paramiko software installed are forcibly mounted as read-only.

FortressSSH aka Pragma SSH Server

ServerID: Pragma FortressSSH 5.0.9.2696 and earlier

Symptom:

When a user attempts to view a directory in Windows Explorer in any view mode other than Small Icons, List, or Details, the files of some types in that directory are truncated and have zero size after listing. Application files (with EXE extension) are truncated even in the specified view modes. Also, files of any type are truncated when the user attempts to open a file (even for reading) in any program or to launch a program from the drive.

Reason:

Version 5.0.9.2696 (and earlier versions) of Pragma SSH Server always truncates files opened for writing, even those which were not requested to be truncated. When Explorer shows a directory in a view mode other that Small Icons, List, or Details, it creates a preview picture for files of some types (thumbnails). To do this, Explorer opens each file and reads some part(s) of it. But because SFTP Net Drive always opens files for reading and writing (with no "truncate" flag set), the files are erroneously truncated by the server software.

For executable files (with EXE extensions), Explorer always attempts to extract their main icons. This means that these files are truncated all the time when a directory is showed in Windows Explorer.

Solution:

Update the server software. The server software since version 5.0.9.2841 does not truncate files.

ServerID: Pragma FortressSSH 5.0.9.2696 and earlier

Symptom:

When a user attempts to copy a new file to the server or to replace an existing file, the copying process finishes successfully, but a bit later the file appears to have zero size.

Reason:

The reason for this problem has not been found.

Solution:

Update the server software. Server version 5.0.9.2841 (and later) works fine in these cases. Drives for servers with earlier versions of this software are forcibly mounted as read-only.

ServerID: Pragma FortressSSH 5.0.9.2841 and later (last tested with 5.0.10.273)

Symptom:

When a user attempts to connect to the server, SFTP Net Drive shows error message "SFTP component not connected" and closes the connection.

Reason:

When the drive is mounted, Windows requests the special file named "desktop.ini" from this drive. The server says that the file exists (although there is no such file available) and it has zero size, and then closes the connection. The same issue might appear for the file named "autorun.inf".

Solution:

Update SFTP Net Drive. Since version 3.0.33, the program forcibly disables special Windows files for such server (i).e. no requests for such files are sent to the server). Instead, Windows is notified there is no such file available.

Core FTP

ServerID: CoreFTP-0.x.x (last tested with 0.3.3)

Symptom:

When a user attempts to copy a file from the server, Windows shows a "Permission denied" or similar error message.

Reason:

SFTP Net Drive always opens files for reading and writing on servers. This server software cannot read from files opened in such mode and reports "Permission denied" error.

Solution:

No solution found. Drives for servers with Core FTP software installed are forcibly mounted as read-only.

ServerID: CoreFTP-0.x.x (last tested with 0.3.3)

Symptom:

When a user attempts to copy files to the server, Windows sometimes shows an "Unexpected error" message (if the file is copied by other program, it can show other error message). But if the user tries to copy the failed file again, the file is copied successfully. Even if files are copied to the server successfully, they cannot be read from the server (see the issue above this one).

Reason:

The server software sometimes reports an "end of file" error while writing the file. Also the server sometimes reports a "no such file" error when Windows attempts to resize the file being copied in order to have enough space for the file data. SFTP Net Drive in its turn reports these errors to Windows.

Solution:

No solution found by now. Drives for servers with Core FTP software installed are forcibly mounted as read-only.

GlobalSCAPE EFT

ServerID: 1.xx_sshlib GlobalSCAPE

Symptom:

When a user attempts to copy a file to the drive mapped to such server, "Could not find this item" error is displayed by Windows.

Reason:

The server reports "File not found" error when SFTP Net Drive attempts to resize a newly created file.

Solution:

No solution found by now.