Issue:
When using MetaDefender MFT to pull files from an SFTP server, jobs may enter a Stalled state if a connectivity interruption occurs during transfer. This behavior applies to both On-Demand and Scheduled pull jobs and is expected by application design.
A job is marked as Stalled after approximately 60 seconds without data transfer. However, this state does not always indicate a failure. In some cases, the job may still be actively processing a large file, performing backend operations, or waiting on I/O, even though no data is currently being transferred.
MetaDefender MFT does not automatically resume or retry an active SFTP pull job after a connectivity interruption. Manual user action is required to restart the job.
Troubleshooting
To minimize stalled jobs, verify the following connectivity and stability aspects between MetaDefender MFT and the SFTP server.
- Network Connectivity Validation
Ensure stable and continuous network connectivity between the two servers:
- Verify no intermittent packet loss or high latency
- Check for firewall or security appliances between servers
- Ensure required ports (default TCP 22) are consistently allowed
Recommended tests:
- Continuous ping between MFT and SFTP server - Traceroute to identify unstable network hops
- Firewall and Security Device Inspection
Firewalls, IPS/IDS, or deep packet inspection devices may:
- Terminate long-lived SSH/SFTP sessions
- Enforce idle connection timeouts
- Reset connections during file transfers
Actions:
- Review firewall session timeout values - Increase SSH/SFTP idle timeout thresholds - Whitelist MFT and SFTP server IPs if applicable
- SFTP Server Configuration Review
Confirm the SFTP server is properly configured for long-running transfers:
- SSH keepalive settings enabled
- Sufficient session timeout values
- Adequate resource limits (CPU, memory, file descriptors)
Common SSH parameters to review:
- ClientAliveInterval - ClientAliveCountMax - MaxSessions
Log Analysis Review logs on both sides:
MetaDefender MFT Logs
- Look for SFTP connection failures
- Session timeout or socket reset messages
SFTP Server Logs
- SSH disconnects
- Timeout or keepalive failures
- Forced session terminations
Cross-referencing timestamps is critical to identify the root cause.
Resolution:
To continue the transfer after ensuring the proper connectivity between two servers:
- Navigate to Jobs in the MFT UI.
- Locate the stalled job.
- Re-enable the job.
Once re-enabled:
- MFT initiates a new backend execution cycle.
- The job is restarted as a fresh execution.
- Any partially transferred files are downloaded again from the beginning.
As a result - the job successfully continues and completes the download.
