Syncthing often does not detect file change (have to manually click "rescan" button each time)

Hi, thanks for the application! However, as is mentioned earlier in Syncing latency is very large and sometimes even does not sync, often it does not detect file change at all (even with fswatcherdelays="2"); clicking the scan button does help though. I am happy to provide logs or enable whatever debug flags to debug this (cannot reply on that thread since it was locked).

I would suggest you start by providing some more information; what operating system you’re running on, any particularities about where the files are stored, and screenshots of the GUI with the folder in question expanded.


  • Sync between MacOS and Ubuntu
  • Using docker container
  • Files are mainly some code (.py etc)

Looks like Syncthing thinks watching is up and running. There have been issues over the years with Docker eating the events though, so I’d probably start there.

As cool as Docker is, at least for Syncthing, you usually end up with a net loss. The container filesystem is pretty pointless because we’re shipping a single static binary and the network isolation breaks local IP detection.

For Ubuntu/Debian I’d always recommend our APT repo as the preferred solution.

Hi, thank you for the replies!

However, if possible, I do hope Docker can be used. For example, this is more unified (I have one single docker-compose.yml containing a dozen of services, and one single docker compose up is enough to start and manage all of them), has better isolation, has unified logging, etc. I personally do not worry about IP detection since I fix them manually. Is there any ways I can still use docker?

EDIT: Additional information: Seems that the Ubuntu side works well, while MacOS does is not.

Are you running Syncthing for Linux under Docker on macOS in a VM, with a mapped volume from macOS, expecting filesystem notifications to work? I think you can forget about that. Run the native macOS version for working filesystem notifications on macOS.

Yes I was doing that, OK I will use the native version… Thank you!

(However, it would be great if the docker version can be used in the future!)

That would be great, but that’s a feature request on macOS, the virtualisation framework, or maybe Docker. It’s not something Syncthing can do, because filesystem notifications simply do not get propagated from the host through all the virtualisation layers to Syncthing.

Totally agree. Btw thank you for the fast reply and finding out the problem - I did not expect replies so actively!