0X00000921: No Shared Communication Devices Fix

Cause 1: Print Spooler Service Stopped or Corrupted

Most of the time, this error is the print spooler service acting up. I've seen it on a dozen different machines — Windows 10 Pro, Windows 11 Home, even a Windows 7 relic that wouldn't die. When the spooler isn't running or its cache is corrupt, Windows can't see shared printers or modems. The error code 0X00000921 with NERR_NoCommDevs is the result.

Fix It

1. Press Win + R, type services.msc, hit Enter.
2. Scroll to Print Spooler. Double-click it.
3. If it's stopped, click Start. If it's running, stop it, then start it again.
4. Set Startup type to Automatic.
5. Apply, OK, then close Services.
6. Now clear the spooler cache. Open File Explorer and go to C:\Windows\System32\spool\PRINTERS. Delete everything inside that folder. Yes, everything. Don't worry, Windows recreates it.
7. Restart the Print Spooler service again from Services.

That's it for the first cause. Reboot your PC, then try sharing the printer again. Had a client last month whose entire print queue died because of a corrupt spooler cache — this fix got them back online in 5 minutes.

Cause 2: SMB 1.0/CIFS File Sharing Support Disabled

If the spooler fix didn't work, the next culprit is SMB 1.0. Microsoft disabled this by default after the WannaCry attacks in 2017. Problem is, older network printers and devices still rely on SMB 1.0 to announce themselves on the network. Without it, Windows can't see any shared communication devices, and you get 0X00000921.

I know — security nerds will scream. But if you're on a private, isolated network with an old printer, turning on SMB 1.0 is the pragmatic fix.

Fix It

1. Open Control Panel > Programs > Turn Windows features on or off.
2. Scroll down, check the box for SMB 1.0/CIFS File Sharing Support. Expand it — you'll see three sub-options. Check all three:
• SMB 1.0/CIFS Automatic Removal
• SMB 1.0/CIFS Client
• SMB 1.0/CIFS Server
3. Click OK, let Windows install the feature. You'll need to restart.

After reboot, test your shared device. If the error's gone, great. If not, move to cause 3.

Cause 3: Network Discovery and File/Printer Sharing Disabled

This one's almost too simple, but I've seen it trip up plenty of people. Windows 10 and 11 have a habit of switching network profiles to Public, which kills discovery and sharing. Your device might be physically connected, but Windows won't let it talk to the network.

Fix It

1. Open Settings > Network & Internet > Ethernet (or Wi-Fi, depending on your connection).
2. Click your network name. Under Network profile, select Private.
3. Go back to Settings > Network & Internet > Advanced network settings > More network adapter options.
4. Right-click your active adapter, choose Properties.
5. Check that File and Printer Sharing for Microsoft Networks is checked. Uncheck it, apply, recheck it, apply again. It forces a reset of the binding.

Still no luck? Open Control Panel > Network and Sharing Center > Change advanced sharing settings. Turn on Network discovery and File and printer sharing for your Private profile.

Quick-Reference Summary Table

That's the three fixes I've used in real-world scenarios. If none of these work, you're likely dealing with a hardware issue — bad network adapter or a dead device. But 9 times out of 10, it's one of these.