This just started happening to us Wednesday. Finder crashes, if you try to Relaunch it just hangs. If you go to another app and get the Menu Bar back and Shut Down it doesn't shut down all the way. Hard shutdown required. Major pain. It's also preventing me from connecting to the Win 2012 server via our Sophos VPN. I have a Macbook sitting next to me running Sierra and it works fine. At least via the VPN using CIFS doesn't change anything, neither does changing SMB packet signing settings https://support.apple.com/en-ca/HT205926

Got a workaround that worked in our organization.

This changes for macOS the SMB behavior to v2
Changed beneath setting in the /etc/nsmb.con file.

#!/bin/sh

echo "[default]" >> /etc/nsmb.conf
echo "protocol_vers_map=2" >> /etc/nsmb.conf

exit 0

For now, no more finder crashes.

Cheers,
Thijs - bol.com

Thijs,

This is great - I wish that Apple had suggested this work around to me. I figured there was a way to disable SMB3 but couldn't find it. The docs I found on nsmb.conf on the Apple Developer site did not mention the protocol_vers_map feature. I've had to support and troubleshoot a number of issues with CIFS and software that is establishing/maintaining it's own connection.

So far this morning this one seems to resolutely resolve all issues until Apple has a patch for its broken SMB3 implementation with 10.13.2.

@ch3valier
Great to hear!

Cheers,
Thijs - bol.com

@txhaflaire Hi

Do you have an Enterprise Support case number?

@txhaflaire

I created an account JUST to say you completely solved my issue!!

Thank you so much.

@NaeemTHM
Great that it solved it temporary for you!

@andysemak
Sure, what do you need it for?

Apple asked me to test 10.13.3 beta and verify if the problem still there, havent found the time to test the beta.

Cheers,
Thijs - bol.com

I tested it last on 10.13.3 beta 2 and it was still broken, haven't had a chance to update to beta 3 (or 4 which I just found out was released). Forcing SMB2 worked for me in my test environment, which is a VM running Windows 2012 R2 server and a machine running 10.13.3 beta 2.

Apologies in advance. Noob here. I am a single MAC running in a windows environment and I am experiencing the Finder lock up with shares on the server described here. It is very much limiting my ability to work efficiently. Plus having to hard reboot is playing havoc with my attached USB Time Machine backup drive. Already had to erase it twice and I am having to disconnect it after a manual backup to maintain its integrity.

When I try to execute the code to limit SMB communications to SMB2 I get access denied. I have tried adding SUDO to each line but that doesn't work. I went to Apple support and tried to do it per this article https://support.apple.com/en-us/HT208209 but again access denied.

Can someone here tell me how to execute the commands properly and how I can check that they were done. I assume that the /etc/nsmb.conf is a hidden file in a hidden folder under /system/library/ but that is just an assumption on my part.

I do have Admin rights for my user. Do I need to enable and log in as the root user (having read that this is potentially a dangerous thing to do).

I know that I know enough to be dangerous but not enough to keep me out of trouble. Thanks in advance.

So the "protocol_vers_map=2" solution seems to work 50/50, the half that it doesn't work for receives an Access Denied when trying to authenticate against the server (Win 2012r2). In the server log I find the following message:

"SMB Session Authentication Failure

Client Name: x.x.x.x
Client Address: x.x.x.x:49219
User Name: DOMAINuser
Session ID: 0x1234567890
Status: The remote user session has been deleted. (0xC0000203)

Guidance:

You should expect this error when attempting to connect to shares using incorrect credentials.

This error does not always indicate a problem with authorization, but mainly authentication. It is more common with non-Windows clients.

This error can occur when using incorrect usernames and passwords with NTLM, mismatched LmCompatibility settings between client and server, duplicate Kerberos service principal names, incorrect Kerberos ticket-granting service tickets, or Guest accounts without Guest access enabled"

Any ideas?

@mbeach

To verify that the nsmb.conf file is changed do the following;

• Finder > Go > Go to folder > /etc


• Search for the nsmb.conf file


• Open the file with textedit oi.


• Check if the file has the value's in it.


• If the file is not there, there went something wrong en let us know!

Cheers,
Thijs - bol.com

@txhaflaire

Can you give a little more detail? I have a few Mac's in our office doing this but making a nsmb.con file then pasting the code doesn't fix the problem for us.

Im using exactly what you posted.

!/bin/sh

echo "[default]" >> /etc/nsmb.conf
echo "protocol_vers_map=2" >> /etc/nsmb.conf

exit 0

@thijs
Thanks Thijs,
Your solution was just what worked, now I can relax and my client is happy again.
Thank you one more time, it really make my day

Thanks guys for working on this. I have had the same issue since December.
@txhaflaire I can't find the nsmb.conf file when going into the /etc folder (hidden files are shown). Do you have any suggestion why that is? Thanks man

@mantos nsmb.conf doesn't exist until you create it with the script above.

10.13.3 Beta 4 is supposed to fix these SMB3 problems.

@Tekniqueman Hmm can you verify the nsmb.conf file is created in /etc/ with its variables in it? screenshot oi.

@mantos No Problems! just remind your self when upgrading to 10.13.3 the fix will applied by Apple and you can remove that specific file on all your clients.

Cheers,
Thijs - bol.com

@cbrewer & @txhaflaire Thank you, sorry for having to ask again: I pasted the code

!/bin/sh

echo "[default]" >> /etc/nsmb.conf
echo "protocol_vers_map=2" >> /etc/nsmb.conf

exit 0

in the terminal and this is what I get:

Last login: Mon Jan 15 15:47:46 on console
MacBook-Pro2:~ manu$ !/bin/sh
-bash: !/bin/sh: event not found
MacBook-Pro2:~ manu$
MacBook-Pro2:~ manu$ echo "[default]" >> /etc/nsmb.conf
-bash: /etc/nsmb.conf: Permission denied
MacBook-Pro2:~ manu$ echo "protocol_vers_map=2" >> /etc/nsmb.conf
-bash: /etc/nsmb.conf: Permission denied
MacBook-Pro2:~ manu$
MacBook-Pro2:~ manu$ exit 0

No file has been created. Seems like I have no permission even though I have admin rights.

@mantos No worries, we will help you out.
Currently you are trying to throw a complete shell script into the terminal.

If you want to do it directly via terminal do the following each line at a time.

sudo -s
echo "[default]" >> /etc/nsmb.conf
echo "protocol_vers_map=2" >> /etc/nsmb.conf
exit

If you want to create a script use a texteditor like TextMate / Textwranger and you can drag and drop it into the terminal.
First a sudo, than throw in in the terminal.

Cheers,
Thijs - bol.com

10.13.3 beta 4 seems to have resolved the issue for me, anyone else? I don't know if I am jumping the gun and just got lucky that Finder didn't freak out.

@txhaflaire you are fabulous, thank you! I did it and it created the nsmb.conf file which I then opened with text editor and pasted in it:

!/bin/sh

echo "[default]" >> /etc/nsmb.conf
echo "protocol_vers_map=2" >> /etc/nsmb.conf

exit 0

@jakobstockman - we had the same issue: the protocol_vers_map=2 workaround was effective for some users but not others. Got exactly the same authentication failure you did, once set. Having removed the affected macs from the domain and readded them (and reset the user's password) the authentication failure went away and he could successfully connect to the share using SMB2.1 (confirmed with smbutil).

@jakobstockman - We observed the same behaviour: forcing SMB2 on the client side sometimes works but sometimes produces the described authentication issue. (We're on Server 2012r2 for the domain controller and file servers.) We found you can fix the authentication issue by re-binding the affected machine to the domain (from Directory Utility, remember to reboot between unbinding and re-binding).

Has anyone tried deleting the nsmb.conf file in /etc/ ? I've done this and then created a new one with the instructions from this somewhat old Apple support doc where it says 'If your macOS computer doesn’t have an /etc/nsmb.conf file'.

https://support.apple.com/en-us/HT205926

So far this seems to fix issues in my environment, but still to soon to say for sure. Still testing, but thought I would put this up.

@txhaflaire

Just wanted to say thanks for being so dillegent about posting your findings and workarounds. Saved having to re-image some machines.

I hope that Apple puts out a fix soon that will address the problem, AND will let us know -- more worried about the second part than the first.

@all macOS High Sierra 10.13.3 just released, they mentioned the finder issue should be resolved.
If any outcomes, great to hear!

Cheers,
Thijs - bol.com