SSP and SSPI back up fails with this error. sftp: closing ssp_backup.tar.gz.enc after writing failed: sftp: "Extension [email protected] is not currently" (SSH_FX_OP_UNSUPPORTED)

Products

• VMware vDefend Firewall

Issue/Introduction

When you use GoAnywhere SFTP server on Windows 2019 server as backup server on SSP and SSPI and try to run backup, you see this error. 

sftp: closing /vcf/ssp/ssp/ssp.abc.com/5.1.0-0.0-25009250/2025-12-9/ce2e6dfa-6a01-4385-b1ca-2154bf0b968b/ssp_backup.tar.gz.enc after writing failed: sftp: "Extension [email protected] is not currently supported." (SSH_FX_OP_UNSUPPORTED)

Environment

SSP 5.0.0.0 and 5.1.0.0

Cause

• SSP uses OpenSSH-style SFTP client with fsync, and GoAnywhere SFTP server does not support [email protected].
• SSP successfully connects to the SFTP server. It starts writing the encrypted backup file.
• When SSP tries to finalize the file, it issues an fsync request. Server replies with extension not supported.
• Even though file upload is successful. fsync operation fails, so SSP marks the backup as failed.
• This is caused due to incompatibility of backup server with SSP and SSPI.

Resolution

Workaround

Use an OpenSSH-based SFTP server as backup server.