Once in a while Finder stops connecting to SMB shares.

Finder → Cmd+K → Connect → It shows a window like this infinitely: Finder connecting to SMB infinitely

What I've tried already:

  1. I have tried connecting to multiple shares (Linux, Windows), Finder didn't connect to any of them
  2. Connecting with alternative client works. For example, Kodi media player includes its own SMB client and it connects just fine.
  3. Connecting from other running Mac works too
  4. Reset Finder settings by deleting ~/Library/Preferences/com.apple.finder.plist
  5. Kill Finder with killall Finder command
  6. Add username and password explicitely into the Cmd+K connect to server dialog: smb://myusername:mypassword@

I assume this is a macOS SMB client issue.

This issue will go away with reboot. I'd like to fix the issue without restarting macOS – how can I restart SMB services only?

  • There’s no daemon for the SMB client like there is for the server. When you run into this problem, use Terminal and list the existing mount points; type mount in Terminal. If there’s already a connection to the server, try unmounting those volumes and then try your mount again – Allan Mar 24 '20 at 13:18
  • I have no mounted network drives; mount command lists only local APFS drive related mountpoints. – babca Mar 24 '20 at 16:06
  • A couple of things...can you try in Safe Mode (Hold Shift while booting)? Also, if possible, install an earlier version of macOS (don't wipe your internal drive!) to an external drive (flash drives are cheap now) and boot from that and see if the problem goes away. You're not reinstalling macOS, just putting a different version on a removable drive for testing. I have a suspicion it's an issue with Catalina. – Allan Mar 24 '20 at 19:52
  • 1
    I can simply reboot the Mac and the problem goes away, but I'd like to fix it without rebooting and interrupting running programs - that's the key point of the question. There must be a Terminal command for that. – babca Mar 24 '20 at 23:09
  • It’s not necessarily a Terminal command. The client isn’t working properly so we have to diagnose it. It could be a conflicting 3rd party app or kext; Safe Mode will help diagnose that – Allan Mar 24 '20 at 23:13

I had the same problem, solved it by launching Activity Monitor and stopping netbiosd process, it gets restarted and then the connections started working immediately. It's possible that I also stopped NetAuthSysAgent process as well, so if it doesn't work for you with the netbiosd process only, try stopping NetAuthSysAgent as well.

  • FWIW I stopped netbiosd and it wasn't until I stopped NetAuthSysAgent that the connection started working immediately – RazerM May 29 '20 at 16:11

As stated by @yssup - Using the mac "Activity Monitor" tool to stop "NetAuthSysAgent" solved the problem for me.

Note that stopping "netbiosd" did not solve the problem.

Ideally one would do this by clicking on a shortcut to a shell script which could stop "NetAuthSysAgent" more quickly and efficiently. However, I cannot figure out the correct shell command to stop "NetAuthSysAgent" programmatically. Perhaps someone else can answer that here.

  • I too have had this problem, and killing NetAuthSysAgent does fix it. Presumably, you could just use killall in shell script, as killall does take a process name as an argument. – benwiggy Jun 9 '20 at 21:45
  • Thanks! I'm using the command "sudo -S killall NetAuthSysAgent" in a script now, and it seems to work to solve the problem. For instance, I had a file management program which would hang and refuse to shut down when the problem occurred, but when "sudo -S killall NetAuthSysAgent" is issued, then the program shuts down instantly and everything seems to works fine when the program is re-run. – TFabris Jun 10 '20 at 19:20

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