Need help with syncthing permission errors. Cannot get sync started

Apps and Virtualization
1

Setup

  • Proxmox host
  • TrueNAS 25.04.2.4 VM (4 cores, 10GB RAM, passed-through ZFS array)
  • Syncthing installed as TrueNAS app with host networking enabled
  • Windows 11 PC running SyncTrayzor
  • PC and Proxmox both have dual NICs.
    – NIC 1 is a 1Gbps connection on 10.0.0.0/24 for general networking
    – NIC 2 is a 2.5 Gbps direct connection between the machines with a 10.0.2.0/24 IP address with no gateway for faster direct 2.5Gbps connection.
    *Both my PC syncthing and Truenas Syncthing app have those IPs hard-coded to force that connection.

My problem

Syncthing creates directory structure successfully but fails to complete sync with repeated errors in logs. This is one I was getting a ton of:

chmod /vault/Documents/[path]: operation not permitted
  • Syncthing creates folders and .tmp files in the destination but cannot rename them to final filenames
  • Sync from Windows PC (D:\Documents) to TrueNAS (/vault/Documents) not completing

Verified Working:

  • I can manually create/modify/delete files in /mnt/Tank/Vault/Documents
  • Syncthing can see the correct path (/vault/Documents inside container)
  • Devices are connected and folder is shared between them

I’m about to pull my hair out. I’ve thought about disabling permissions, but I’m not really sure that I want to do that. And I’ve seriously considered finding a different solution altogether, but I really like some of the features of syncthing, and would love to get it working since I am right at the finish line.

I have access to a premium subscription to Claude AI with work, so I’ve been trying to leverage that for help, but I just keep going in circles. (yeah, yeah. hate away. haha)

Can someone help me please?

2

Hello, I’m having the same issue, where I’m trying to sync a few systems that work fine between them using syncthing, but I’m having the same issue with truenas and permissions.

In my case it also creates the folder and files (.tmp) but will not rename them. I don not get any specific error, just that the folder failed to sync.

I can get passed this if I check “Ignore permissions” on the truenas system, but although I can use the files after, I’m not how this will impact future handling of files.

Have you found a solution to this?

For info: i have added a Dataset (SMB preset) and added the apps user with modify permissions on it.