OS X 10.9 Mavericks Workaround for SMB

Upgrading is never easy. There is always some new bug introduced as a feature. That said, you may have noticed that connecting to NAS shares worked perfectly in OS X 10.8.x but doesn’t anymore in OS X 10.9 (Mavericks). Here’s the lowdown:

DISCLAIMER: Though these are pretty harmless changes, any changes you make are at your own risk.

Issue

Clients logging into File Services over SMB with OS X 10.9 experience a hanging connection upon login attempt.

Root cause

OS X 10.9 now utilizes a new SMB2 stack written by Apple. Apple’s SMB2 implementation was not compatible with many other SMB2 NAS products on the market at the time, while Windows 7, 8, and 8.1 worked just fine. In short, it was an Apple bug. It’s a good idea to restart your Mac before trying to connect to your storage again — this clears any hung SMB processes from previous attempts.

Workaround option 1: per-connection SMB1

To force a single connection to use SMB1, type cifs://servername instead of smb://servername when connecting to a Windows or NAS share. By far the easiest option, and it requires no configuration changes.

Workaround option 2: force SMB1 system-wide

Open a Terminal window and paste the following on one line, followed by Return:

echo "[default]" >> ~/Library/Preferences/nsmb.conf; echo "smb_neg=smb1_only" >> ~/Library/Preferences/nsmb.conf

• What it does: creates ~/Library/Preferences/nsmb.conf and adds a directive that forces SMB connections to negotiate SMB1 — slower, but stable with the buggy NAS firmware of the day.

To remove the workaround, open a terminal window, paste the following at the prompt and hit Return:

rm ~/Library/Preferences/nsmb.conf

Source: cammodude (link verified live).

Reading this in 2026?

• The nsmb.conf mechanism itself is still current — modern macOS reads the same file, and sysadmins still tune it (for example signing_required=no or protocol_vers_map) to fix SMB performance on NAS boxes.
• But the SMB1 part is gone. Modern macOS no longer supports SMB1 at all; the cifs:// prefix no longer forces an SMB1 connection because there is no SMB1 client left to force.
• If a NAS share misbehaves today, the fix is on the server side: update the NAS firmware to a current SMB2/SMB3 implementation (Synology, QNAP, TrueNAS and Samba all speak SMB3 now), or check Apple’s current guidance on connecting Mac to shared computers and servers.