We've got a chroot environment on CentOS set up for our users to download data from. One of our users is using WinSCP and they're getting this error:

"A call to an OS function failed".

This link on the WinSCP Support forum raises the same issue but there's no response. It appears that the problem is that the chroot environment is passing back a double backslash "\" in the directory name, which is confusing WinSCP. Has anyone had the same problem and knows how to solve it?

  • My current suspicion is that it's because the users home directory in /etc/password has a '/' on the end of it but my change hasn't seemed to make a difference. That said, I don't know if I've successfully managed to get sshd to reread /etc/password.
    – Anonymous
    Jan 7, 2010 at 20:32
  • any update to this issue? the forum post you link to shows an error when a file is edited. can winscp copy the file OK? Feb 20, 2010 at 5:15

2 Answers 2


In Winscp Go to Options-->Preferences-->Endurance-->Enable transfer resume--> All files Click on OK and then refresh Winscp. The error should not come.

  • 1
    Do you have any references or an in-depth explanation why changing the settings in this way would help the issue? In the end, it simply changes the resume settings and does not look very promising at solving anything here.
    – the-wabbit
    Jul 24, 2013 at 12:01

This error would rather seem that the chroot is incorrectly set up and is missing essential libraries. What is the config for the service?

Are you using rssh? If yes, older versions of WinSCP could work only with unrestricted shell (one with cp, chmod, etc.), newer versions support SFTP protocol that works OK.

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