error Mounting Windows share on Ubuntu 16.04

[giobaxx]

A user mounted a windows share using the following command:

sudo mount -t cifs -o domain=mydomain.com,username=Active_Directory_User name , iocharset=utf8,uid=id_local_user //192.168.x.x/share /mount_point

and it worked till some days ago. Now he receive the error below.


[74982.605836] CIFS VFS: protocol revalidation - security settings mismatch
[74982.608695] CIFS VFS: session ffff885158534400 has no tcon available for a dfs referral request
[74982.610651] CIFS VFS: cifs_mount failed w/return code = -5




he told he did only an update, and my collegue told me to try to add the option sec=ntlm so i did

sudo mount -t cifs -o domain=mydomain.com,username=Active_Directory_User name , iocharset=utf8,uid=id_local_user,sec=ntlm //192.168.x.x/share /mount_point

receiving new error

[79103.990605] CIFS VFS: Unable to select appropriate authentication method!
[79103.990609] CIFS VFS: Send error in SessSetup = -22
[79103.990625] CIFS VFS: cifs_mount failed w/return code = -22

There is some error that i don't see? the only way to mount that share now is using the option vers=1


sudo mount -t cifs -o domain=mydomain.com,username=Active_Directory_User name , iocharset=utf8,uid=id_local_user,vers=1 //192.168.x.x/share /mount_point

Could you help to undestand what was happened?

Tanks

[Morbius1]

Maybe the user updated his kernel. There was an update to the Linux Kernel version 4.13 that changed the default CIFS smb dialect from SMB1 ( vers=1.0 ) to SMB3 ( vers=3.0 ).

If the server cannot handle SMB3 then you will need to use an earlier dialect "vers=2.0" or in your case "vers=1.0".

[giobaxx]

Tanks. I will ask to our sysadmin