Troubleshooting General Sync Errors

Fixes for common Sync issues.

The Sync client displays failure to start sync error

When the async binary on the remote computer cannot initialize, the async client gets a generic error similar to the following:

Failed to start sync session

Causes: Possible causes include the following:

  • async binary doesn't exist (or is not in the path and sshd cannot find/execute it).
  • async binary cannot be run.
  • async binary cannot initialize properly (such as when the system is out of memory or socket resources).
  • async binary cannot create its log files, if specified with -R (bad path, bad permissions).

Solutions:

  • Confirm that the async binary is present. Look in the following location:
    /opt/aspera/bin/
  • Confirm that the Aspera license shows that Sync is enabled. Run the following command and look for sync2 in the list of enabled settings:
    # ascp -A
  • If the system is under-resourced, increase the timeout allowed between the start of an async session and the FASP transfers associated with it by running the following command. In this example, the timeout is increased to 10 minutes (600 seconds):
    # /opt/aspera/bin/asconfigurator -x "set_node_data;async_connection_timeout_sec,600"
  • Confirm that the path in the argument for -R is valid and that the Syncuser has write permissions to the directory.

Never-ending bidirectional session, with one file stuck in "pending" state

Causes: This can happen if a file is not in error for Sync but is in error for the underlying ascp process. For example, when async is run with --checksum=none and access to the file is denied, async does not open the file to calculate a checksum so it does not recognize that the file is unavailable, but ascp cannot open the file and reports an error. This can also happen if a file is truncated during the initial synchronization; the server ascp reports an error but the client ascp does not.

How to recover: Stop the Sync session by running the following command:

# asyncadmin -d path -N name -T

Check file permissions on the source and destination, and confirm that files are no longer being modified. Rerun your Sync session. You do not need to use -x.

Async fails with no specific reason

Causes: This can happen if the async user does not have permission to the files. This problem often arises when scripts are used to write files to one of the endpoints and the system permissions are overridden. Check the user's permissions to the files.

How to recover: Stop the async session by running the following command:

# asyncadmin -d path -N name -T

Edit the script to write files with the correct permissions, and rerun the async session.

Error returned when you try a synchronization from Linux to Windows.

When you try to synchronize from Linux to Windows, you receive the following error:

Failed. Peer error: Symlink policy copy not supported on Windows peer.

Solution: Specify -n skip or --symbolic-links=skip when performing the synchronization.

Error returned when you synchronize two locations on the same computer

You can synchronize files between two locations on the same computer. If you only enter the "remote" directory, such as -r /tmp/, then async fails with the following error: 
Failed - Error, must specify remote-host name

Solution: Specify the remote host and path as -r username@127.0.0.1:filename.