Scheduled sync job fails

English Backup and data protection
1

A single scheduled sync job fails, but if I run the same job manually, it works fine. The destination is another QNAP NAS

In the logs, I can see:

System.log:
6881, 2,2025-12-22,04:51:17,System,—,localhost,[Hybrid Backup Sync] Failed to complete Backup job: “XXY_Backup”. Folder pairs are invalid or inaccessible. Error code: -50, 41,1766375477,A200,Hybrid Backup Sync,C002,Job Status,legacy_qtoken_client_id_admin_0,localhost,Agent,

job_log.csv:
system,5b11ed7e-c204-11f0-84a6-aa27aa27f9b1,error,2025-12-22T04:51:17.2438+01:00,“[Hybrid Backup Sync] Failed to complete Backup job: “XXY_Backup”. Folder pairs are invalid or inaccessible. Error code: -50”

I have tried removing and recreating the sync job, everything works fine on the first manual run, then it fails on the next scheduled run.

Any ideas?

2

If you run it manually a second or third time does the sun job work? And what kind of a sync job? Two way? One way? Active?

3

Looks like it struggles on the second run. It is an Active sync job. The job is stuck at 5% and the log I’ve found in /share/ZFS2_DATA/.@qsync/detail-logs shows the following at the moment:

[2025/12/22 21:21:59] Schedule type: Manually.
[2025/12/22 21:21:59] The deleting extra files option is disabled.
[2025/12/22 21:21:59] The checking data content option is disabled.
[2025/12/22 21:21:59] The detecting sparse files option is disabled.
[2025/12/22 21:21:59] The extended attributes option is disabled.
[2025/12/22 21:21:59] Symbolic link files are included.
[2025/12/22 21:21:59] The detail log is enabled with the maximum size 10 MB.
[2025/12/22 21:21:59] The TCP BBR congestion control option is enabled.
[2025/12/22 21:21:59] Use network adapter qvs0 (10.16.11.103) for outgoing traffic.
[2025/12/22 21:21:59] Maximum retry times: 5; Retry interval in seconds: 180; Connection timeout in seconds: 60; Current retry number: 0.

4

After I’ve cancelled the second run, the third went through without any problems. The log shows no clue whatsoever.

[2025/12/22 21:33:40] Job [NAS_CFG_Backup] started.
[2025/12/22 21:33:40] Synchronize files from a local folder to a remote folder.
[2025/12/22 21:33:40] Server IP address: 192.168.110.101, port number 8899.
[2025/12/22 21:33:40] The SSL connection option is enabled.
[2025/12/22 21:33:40] The ZIP-compression option is disabled.
[2025/12/22 21:33:40] The number of folder pairs = 1.
[2025/12/22 21:33:40] Pair1 = [Backup/NAS, /Backup/NAS/NAS_CFG_Backup/latest/Backup/NAS/].
[2025/12/22 21:33:40] Schedule type: Manually.
[2025/12/22 21:33:40] The deleting extra files option is disabled.
[2025/12/22 21:33:40] The checking data content option is disabled.
[2025/12/22 21:33:40] The detecting sparse files option is disabled.
[2025/12/22 21:33:40] The extended attributes option is disabled.
[2025/12/22 21:33:40] Symbolic link files are included.
[2025/12/22 21:33:40] The detail log is enabled with the maximum size 10 MB.
[2025/12/22 21:33:40] The TCP BBR congestion control option is enabled.
[2025/12/22 21:33:40] Use network adapter qvs0 (10.16.11.103) for outgoing traffic.
[2025/12/22 21:33:40] Maximum retry times: 5; Retry interval in seconds: 180; Connection timeout in seconds: 60; Current retry number: 0.
[2025/12/22 21:33:49] Created snapshot (Backup/NAS) successfully.
[2025/12/22 21:33:51] Finished synchronizing.
[2025/12/22 21:33:51] Sync statistic: Total number of the folders: 5. Total number of the files: 159. Total updated size: 0 byte. Average updating speed: N/A. Time elapsed: 10 seconds
[2025/12/22 21:33:52] Job finished.

5

So is it working now?

6

If I manually run it a few times, it works, but otherwise, it doesn’t. The secondary NAS is offline for 23 hours a day and starts 20 minutes before all the backups begin. All other active sync jobs function correctly, except for this one.

7

When the synchronization fails, could you please verify if the remote NAS is accessible and connected normally?

Additionally, it might be helpful to check the connection status shortly before the scheduled task is set to run. Thank you!

8

It is accessible. I can access it both via web and the ssh.