A friend of mine worked in another dev shop that reported MacOS networking errors to Apple – fully reproducible. He had nothing good to say about the process. Some issues apparently went on indefinitely. Apple kind of lived up to their snooty reputation.
Maybe it’s better today, but anyone who wants a quick fix might want to learn how to work around the SMB problem.
Not that Plex should not characterize and report the issue, I just wouldn’t hold my breath waiting for Apple to do anything.
What I know of Synology – and MacOS is limited.
MacOS is not actively developing NFS. Apple ‘froze’ development some years ago in favor of SMB
Synology very heavily favors SMB due to its Mac & Windows user base.
Everyone I know with a Mac or Windows uses SMB for their media mounts
They further go into the confirming the ACLs of the files on the Syno
( ACLs will allow you to see it in the browser but make it INVISIBLE in SMB )
^^ #4 is important
When I use Synology with NFS (with a friend’s mac), the same situation existed. I might be able to see it in FileStation but it will be invisible over NFS. Root cause – ACLs.
Whenever I tried to report issues, I got a lot of finger pointing. I eventually gave up
If this were Linux, I could easily tell you how to fix things
I wrote a Python script to “thrash” my SMB share by adding and deleting files, then checking to see if the directory contained the expected files. It does this repeatedly over time. I was able to get it to fail on occasion when I started my testing (with 1,000 files), and when it did fail, it would report about half as many files as I had in the folder.
Maddeningly, though, I can no longer get it to fail reliably or repeatedly, frustrating my attempts to narrow down the cause. I’ll continue to explore, hoping that I can find a better clue.
Adding the data point of one more with this issue.
Mac Mini running 15.1 going back to a Synology NAS. One my end I could see Finder getting confused and dropping files periodically which would then coincide with trash cans on plex. Not all files just about half of the ones in my Movie directory. Tried disabling directory leasing and opportunistic locking. Seemed to help for a little while, took longer to get trash cans but that might have been a placebo effect.
Its funny for some reason I didn’t automatically search online when this problem cropped up for me. Just spent the last two days futzing with this trying to figure it out. Made it to the NFS step but don’t want to go that route. Finally decided to google everything and here you all are. Happy Thanksgiving all! 
Oh well, looks like my aging windows plex server is going to have to keep chugging along for a while longer.
And this is exactly what the Plex devs have been saying, and being ignored. This is a Mac os issue, if you can recreate the issue in python you confirmed that it isnt isolated to plex. Thus this is something Apple will need to address.
Except that if we can reliably reproduce it, we can probably also work around it. Either with the right configuration settings, or the right changes to the app’s behavior. It’s common for software developers to have to work around known issues with the underlying operating system or SDKs.
Exactly this… What I would like to see is Plex devs to add in the ability for direct SMB connections, rather than relying on the OS SMB mounts. I’m saying this without any idea what all that would entail for them to do, but I think in the long run it would provide better performance for anyone using a NAS on any platform, and eliminate OS level SMB issues which seems to be plaguing apple for the last couple major updates.
I can confirm this. It’s easier to duplicate with “lots and lots of tiny operations” than with “a few big transfers”. Definitely not limited to Plex.
Tried running my aforementioned SMB thrashing script a bit more this morning on macOS, and I see failures when the share is hosted on Synology or Windows 11. Curiously, I can’t seem to get it to fail when sharing from another Mac. This is more confirmation that the issue isn’t just limited to SMB shares on Synology devices (which others have also reported). I’ll continue to test.
Great I just got a mac mini m4 and transferred my plex server over to it. Only to realize not all my shows and movies were there and now I’m seeing it’s a common issue.
I have the same problem.
mac mini m4 and synology nas.
NFS seems to be a temporary workaround. I recommend setting the NFS as read only on your NAS. You can find instructions in a previous post of mine.
Leaving the finder windows open to each large folder of your media also works for some.
Be sure to leave empty trash setting OFF in plex, and possibly even automatic library scans.
Okay, after hours of SMB share thrashing with my Python script across macOS, Windows 11, and Synology, I’ve finally landed on a configuration that seems to workaround the issue. I’d love for others to give these settings a try too.
Here is the nsmb.conf file that I’m using on my Mac (located at /etc/nsmb.conf): macOS SMB Configuration to Prevent Directory Caching Issues · GitHub
I suspect (but haven’t confirmed) that the two settings that workaround this issue are dir_cache_off=yes and mc_on=no. I hope this works!
I’ll try this out. I just added this into my /etc/nsmb.conf I’ll keep you posted. Follow up questions I had are do you allow your mac to go to sleep? And do you allow your plex to scan for changes periodically & have the empty trash off?
I added the numb.conf file to my downloads machine first, just to see how it reacts. I’m not sure if this is expected, but both my Macs didn’t have this conf file at all. I also assume this needed at least a finder relaunch to apply and since plex is in use now didn’t want to kick people off just yet. Anyhoo… first thing I noticed is that now my library folders load instantly. There used to be a 3-5 second delay. This seems promising.
I do not allow my Mac to sleep. Before this issue, I did have my Plex scan for changes periodically, but since then, I’ve been doing it manually. I have also turned off the “empty trash” feature…at least until I’m 100% confident of the behavior/fix.
By default, the nsmb.conf file doesn’t exist. This means that the SMB services use their default settings. Adding this file makes it possible to control some of those settings.
If you’ve never had a configuration file like this, it’s likely that these settings will improve your browsing performance, because it disables many of the older SMB features that often need to be re-negotiated when connecting to a share.
Restarting your Mac will definitely pick-up these changes. You can also unmount your share, edit/create the nsmb.conf file, then re-mount the share to pick-up the changes (as far as I know). There is another method I was using, but it’s a little more technical.
Also, if you’ve never disabled the writing of the .DS_Store files that Finder uses to remember folder settings, you can do that too to improve performance: How to Disable the Creation of .DS_Store Files From a Mac. It doesn’t have anything to do with the issue we’re discussing in this thread, but I do it on all of my Macs.
Awesome! thanks for the info. I’m liking the performance of SMB on my downloads server, now that I added the conf file there. I’ll definitely add it to my Plex server once it has some downtime.
Im sad to report that I added the file as it was made to /etc and absolutely NOTHING changed.
restarted more than once, still loads very slowly, and still TRASH CANS if finder is not open. IMMEDIATELY
I’m really happy to have found this thread because I was going crazy! I wiped my Plex instance after having it set up for years, rescanned, and all my files showed up (hooray!). But the next day, about 1,000 files were missing.
It’s been tough to research the issue because most discussions assume the problem is due to incorrect file naming which is not the case, the files are also not deleted they just are not being shown in plex . I’m running Plex Server on a Mac Studio, and the files are stored on a Synology DS1621+.
I discovered that if I open Finder, navigate to my movie files, and leave the Finder window open, then tell Plex to scan, the missing files reappear.
I don’t care who’s issue it is I am just hoping it gets fixed. I installed Jellyfin (before discovering this thread) and woof its a buggy mess over there.
