Posted by on October 17, 2019

After upgrading to macOS Catalina 10.15, your previously working autofs mountpoints may need to be updated with Catalina’s new filesystem structure.

In this example, I was previously mounting NFS shares from my local NAS to a folder named “Nas” in /Users/me. In Catalina, your data moves to a separate volume from the operating system files. (You can verify this in Disk Utility.)

New “Data” mount point in Disk Utiility – Catalina 10.15

So from the perspective of autofs, your previous mount points may no longer exist at the previous location. In my case, the /Users directory moves to /System/Volumes/Data/Users.

To fix my /etc/auto_nas file, I simply prepended each mount point with /System/Volumes/Data:

# Media share
/System/Volumes/Data/Users/me/Nas/media     -fstype=nfs,noowners,noresvport,hard,bg,intr,rw,tcp,rdirplus,rsize=65536,wsize=65536,readahead=128 nfs://my-nas:/mnt/Pool1/media

# Storage share
/System/Volumes/Data/Users/me/Nas/storage     -fstype=nfs,noowners,noresvport,hard,bg,intr,rw,tcp,rdirplus,rsize=65536,wsize=65536,readahead=128 nfs://my-nas:/mnt/Pool1/storage

# Archives share
/System/Volumes/Data/Users/me/Nas/archives     -fstype=nfs,noowners,noresvport,hard,bg,intr,rw,tcp,rdirplus,rsize=65536,wsize=65536,readahead=128 nfs://my-nas:/mnt/Pool2/archives

With your mountpoints corrected, save the file, run the automount command (to flush the cache and reload /etc/auto_master), and get back to enjoying the new OS!

sudo automount -vc

If automount completes successfully, but does not confirm that it mounted your shares, you may need to update your automount master mapping file (/etc/auto_master) as well.

UPDATE (2020-02-01)

A word of caution about using a mount point in your Users directory

While automount points inside /System/Volumes/Data/Users/<you>/ automount successfully, you may encounter a peculiar issue in Catalina where the mappings duplicate over time (seemingly each time they get re-mounted by autofs), and CPU utilization increases to the point of system instability. If you run the mount command, it will report any duplicates, even though you will only see one instance of the mount point in Finder. When the duplication occurs, the automountd process will consume significantly more CPU cycles than it normally would.

The solution is frustratingly simple: move your automounts outside of the /System/Volumes/Data/Users/ directory. After struggling with this for months, I moved my mount points to /System/Volumes/Data/Nas and everything went back to normal (or at least, to how it behaved pre-Catalina).

Relevant threads from discussions.apple.com:

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