How to solve Mac error -9923 when scanning over a network

Updated February 5th, 2022.

Mac error -9923 can occur under some conditions when scanning over a network using an all-in-one printer/scanner/copier. If it does, you might get a message saying “An error occurred when communicating with the scanner.” The result: you can’t scan.

The problem seems to pop up out of nowhere. And printing and copying will continue to work. It’s only scanning that’s an issue. Weird.

If you do a Google search for this issue you will find many totally unhelpful tech “support” responses from HP and Epson (Canon is better). They tell you to uninstall drivers, reinstall drivers, turn the printer/scanner off, turn the printer/scanner on, restart the router, restart your Mac, restart the coffee pot. Total waste of time.

The real answer is in the network settings. You have a choice: adjust the printer’s network settings (harder, but it solves it for the whole office), or adjust your Mac’s settings (super easy, but it only solves the problem for you).

Solving the problem by adjusting the printer’s network settings amounts to turning OFF IPv6 on the printer. This is done various ways, depending on the printer. With some printers, you’ll see a panel on the front, and you’ll go to the Settings, and then Network (or maybe LAN settings), and eventually you will find a place to turn IPv6 off. With other printers, you’ll type the printer’s IP address into a browser, and that will give you control over the printer’s settings. Some printers come with their own Mac app, which you can use to adjust settings. Either way, it all comes down to one thing: you want to turn OFF IPv6 on your printer. (This assumes that IPv6 is off on your Mac. The idea is we want the same settings– on, or off– on both the printer and the Mac.)

The easier way: fix it at the Mac end. Go to Apple menu / System Preferences / Network, then click the Advanced button.

Network preference pane
Network preference pane. Click “Advanced…” button.

After you click Advanced, click TCP/IP (at the top). Then change IPv6 to “Automatically.” Then click OK, then click Apply. Then close the System Preferences window.

Configure IPv6 Automatically
Setting IPv6 “Automatically” in Network preference pane

If IPv6 already said “Automatically” try changing it to Link-local, then clicking OK, then clicking Apply. Then go back in and change IPv6 to “Automatically” again.

If I were you, I’d try changing my Mac’s Network settings first. It’s easy, and easily undone. If it works, great– you’re done. If it doesn’t work, put things back the way they were, and then tackle the problem from the scanner/printer’s end, by changing the printer to disable IPv6.

As you can see, both methods try to match up the Mac’s network settings with the printer’s. In the first case, we change the printer’s settings so it matches the Mac’s. In the second case (the one I’m recommending), we’re changing the Mac’s setting to match the printer’s. Regardless of the method, the proof is in the scanning: if, after changing the Mac’s settings, you can scan, voilá! If you can’t scan, change the printer’s settings (in the printer itself). That should do it.

Note: it wouldn’t hurt to restart whichever device you change (Mac or printer/scanner) after you make the change.

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156 thoughts on “How to solve Mac error -9923 when scanning over a network

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  1. Thanks so much for this! Fixed it!

    I also agree with your points about the official tech support suggestions – it’s always on the lines of uninstall drivers, reinstall, turn off, turn on, put your right foot in, put your right foot out, turn around and shake it all about, reboot the router, reboot your laptop, reboot your life, etc etc etc. A lot of work and rarely works.

  2. I was using Express VPN and I tried disconnecting from it and it reset it without doing anything else and then I turned VPN back on and it seems to have fixed it. Lets see how long that lasts.

    1. Thanks for this tip. I tried the above, which didn’t work for me, but then I saw your comment about disconnecting Express VPN, and now my scanner works. Is that weird??

  3. Thanks! Works perfectly. I just bought a new Canon printer and the scanner wouldn’t work. It was driving me nuts. If you have time, could you please explain why changing this setting will allow the printer to work?

    1. Basically, the “old” style of internet address was IPv4. Addresses look like this: abc.def.ghi.jkl

      That is, the address is in four parts. If you look in your network settings you will see something like this: maybe 192.168.1.x or 10.0.1.x.

      This is all very good if the printer has an address in the same family. And it would, except… somewhere along the way, a new standard for IP addresses (Internet Protocol addresses) was developed, because we (the world) were going to run out of unique IP addresses someday if the addresses were in the IPv4 format. You can see how that could happen.

      So… “they” came up with IPv6, because the addresses are way longer than IPv4 addresses, and therefore there are many times more unique addresses for us to use. Great stuff, except it came out of a committee (which is fine) but there were details that weren’t quite agreed upon, so every implementation of IPv6 networking could potentially be a little bit different, depending on the company that made the networking equipment or card in the device. (For that reason, it is often better to keep using IPv4, at least for the time being.) A lot of devices (including Macs) let you turn on both kinds of networking, and somehow the “right” kind of networking is grabbed and everything is great. Generally, what was grabbed was IPv4.

      For some reason, either scanning over a network is an IPv6 thing only, or your scanner insists on IPv6, so we just have to get our Macs to obtain an IPv6 address, so we can talk to it. It would work either way: tell the scanner to speak IPv4, or tell the Mac to speak IPv6.

      I hope that explains it.

  4. Hi Christian-

    This worked briefly (turning off IPv6 at the printer, Canon TS9120). Now it’s back to the 9923 error after I changed NOTHING. I’m about to throw my printer thru a wall. Any other suggestions? FWIW…I also tried to change the IPv6 address manually at the printer. No luck there either.

  5. Thank you Mr. Boyce, it works for me as well.

    I tried to disable the IPv6 from my printer end (HP DeskJet Ink Advantage 5275). It did’t work. Then, I tried your second solution, which is change the IPv6 from Automatically to Link-local Only to returned it back.

    By the way, I found your site as the first suggestion by Google when I searched for “scanner error 9923”. GREAT 🙂

    Have a good day,
    best regards.

  6. You have made my day. With your instructions I was able to switch off the IPv6 on my Cannon Printer. I tried the Mac solution first but it did not work for me. I’m a very happy 79 year old lady!

  7. Hello. I have HPDeskJet 3630 All-in-One. Everything worked perfectly until we moved into a new apt and I had to connect my HP through network. After 3.5hours when it finally worked, my printer is OK, but scanner function is not working. I tried your advice, but no result. Can you please help what else I can try ? Thank you.

    1. Did you try it both ways: turning ON IPv6 on your Mac, to match the HP, and then the other way (going to the printer, turning OFF IPv6, turning it off on the Mac again?


  8. I changed settings in Network – TCP/IP from Automatically to Manually and then back to Automatically, and then from Automatically to Link-local only and back to Automatically …

  9. well, I went to printer settings via browser but cannot find where to disable IPv6 – I can only put there Manual IP address …but at least I found there webscan and enabled it so in case of emergency I will use it …anyway, thanks for helping me out and if you can advise me, hot to turn off that IPv6, I will be glad …thank you

    1. You’re close. I don’t know what the settings look like for the printer, but you are in the right place. Once you get to the settings in the browser take a screenshot and send it to me– macman at christianboyce dot com. I’ll have a look.

  10. I tried this many times, both on my Mac and on the printer (Brother LCP-L2550DW) and the printer still doesn’t recognize the computer. 🙁

    1. Interesting the way you phrased it: “the printer still doesn’t recognize the computer.” It makes it sound as if you are trying to scan by pressing buttons on the printer and sending it to the computer. I would do it another way. First, be sure you can print from the computer. That’s a quick networking test. Then, go to the Mac App Store and download Brother iPrint&Scan. Here is the link to the app on the App Store: I have a Brother Brother MFC-J430W and this software made it work. The key is, you control the scan from the Mac, not from the printer. Put your picture on the glass, start the iPrint&Scan app, click Scan, and you’re done. If you really want to scan by pushing buttons on the scanner, you’ll have to download “iPrint&Scan Push Scan Tool” (you’ll be asked to do that after installing the iPrint&Scan app). I didn’t install that because I was happy scanning from the Mac, and I didn’t want to mess with something that was working!

  11. Hi,

    I am trying to do this but for some reason the option is unclickable on my laptop. I cannot change any of the advanced settings. Any ideas?

    1. Fantastic. Check out the lectures I’m giving online– see, look for “Lectures,” watch a video or two! Sign up for the mailing list to find out about what’s coming up next. FYI.

  12. I tried everything including restarting the coffee pot, but nothing worked and the problem has continued off and on for 1-2 years. What finally may have worked was unplugging and moving the router off the floor to a higher position with a clearer and less-wall-obstructed line of sight to my devices AND moving the printer to be closer to the router. So far, so good.

  13. Hi Christian!
    I tried both – first by enabling at the MAC end and then by de-enabling at the printer (Brother) end, but neither worked. Is there anything I can try?

  14. Looking for advice on a related problem. Any help would be greatly appreciated. I get that same error message and error number when I try to print (not scan) from my imac (running High Sierra 10.13.6) to my new hp color laserjet pro MFP M182nw printer. After a few days of its arrival, I finally got the printer to print (have no idea what I did to get it to work), but then a few days later it would stop responding (have no idea what I did to get it to not work). In the system preferences panel I opened the print queue and saw the print job listed with the message “Printing — the printer is not responding”. Shortly before buying the printer I read online reviews of it, and although there were many good reviews, there were a cluster of 1 star ratings that cited this exact same problem. No one had a solution though several people mentioned they had contacted hp for guidance but nothing useful came of it.

    1. Hi Alan. I am guessing that your Mac connects to the printer wirelessly. If so, here’s what I would do (with no special knowledge of your printer):

      1. Delete the printer.
      2. Add it again, if possible, via System Preferences. You might have to restart the printer to make that happen. If you do it the automatic way you will probably be using Apple’s AirPrint driver. Assuming you have HP’s driver installed you may want to try it, so don’t set up the printer automatically. That is, click the + at the bottom left of the Printers section of System Preferences. Don’t click on the + and hold it and choose your printer from the list. Click it, let go, and THEN choose it. That’s when you’ll get the chance to use HP’s driver.
      3. Select the printer, still in System Preferences, and look for a button that says “Option & Supplies.” In there, you may see something that says “Printer Web Page.” Click that. A web page will appear, with a bunch of options for controlling your printer.
      4. Look for networking stuff, and if possible turn OFF IPv6. Same advice as for the scanner. You may need to restart your printer for that to take effect.

      Let me know how it goes after that.

  15. Thanks, but it doesn’t work still. I could print, but scanner keep on sending the same message 🙁

  16. Tried just changing the Mac side. Didn’t work. Changed the printer settings. Didn’t work. Kept the printer settings with the iPV6 off and went back to the Mac and switched to link-local, then closed Preferences. Then opened Preferences, and switched to Automatically, then closed Preferences (after clicking on apply)…and it worked! Thank you. Canon TR4520

  17. Cool! In my case, I had forgotten I turned my WiFi off on my Mac. So, the printer was connected via USB cable, but apparently the “scanner” was not smart enough to figure it out. Thus, printing was working, scanning not.

  18. OMG this has fixed sooooo many months’ of headache. Such a simply little fix. This is gold! Thank you!

  19. Many thanks Christian, you’re great.
    Bought the printer yesterday, impossible to scan in wifi.
    Phone to Canon : no solution found !!
    Thanks to you the issue is solved in one minut !

  20. Thank you, Christian! After countless hours wasted trying to find fixes by downloading useless software and years of having to run to my desktop to scan, thanks to your advice, i finally resolved this problem in one minutes and can scan from my MacBook Pro for the first time in..err…years. Cheers!

  21. Hi Christian,
    What setting should I change on the printer itself?
    I tried your solution in my mac but it is not working. I kind of same error on my Linux laptop so I guess it come from the printer itself.
    I already put a fix IP but same result.

    1. If the issue is -9923, it’s a network mismatch between what the printer is doing and what the network is doing. Try to change the printer so it is “speaking” IPv4 only. Then make sure your Mac is also. Let me know how it goes.

  22. Thanks to take time to reply Christian!
    In fact nothing related to the network for my issue. I just find how to solved it.
    I’m having a Canon MG5300 which was in a very old firmware (1.03) and soon I installed the last one (2.02) all goes well from all devices I have.
    All the best,

    1. Awesome. Were you getting -9923 as the error, or did it just not work? Actually I wonder whether the firmware fixed a network problem. IPv6 might not have been included in the original firmware— maybe something else. Did they describe the fixes in your new firmware? I’m curious!

  23. When I’ve start scanning today, I had a half scanned page then the error -9923, on three Macs (Catalina and two high sierra) and on a Linux Debian I only had Failed to communicate.
    I’ve read your post, my mac IPv6 was completely off, I’ve put Local Only as requested, restarted the mac and the printer but still failing.
    IPv6 on this printer can only be selected if you disable IPv4.

    I tried on another Mac which never had this printer configured, and when I looked for the printer driver I’ve seen a “new” firmware.
    So I tried, guessing there were some protocols issues (with new security update or upgrade) because my first Mac didn’t have this error before, not the case on the Catalina’s one which always had since it was upgraded to, and voilà, works back on all computers I have at home.
    Regarding the firmware details, there is nothing: AirPrint firmware updater will upgrade your printer’s firmware to version 2.020
    I didn’t tried to scan over cable, may be it was working, I don’t know.
    Hope it can also helps other if they have the same model as me.

  24. HI Christian, I can not change the IPv6 in my Mac. Do you know how? I did it in the printer but did not work

  25. Thanks a mill it worked for me. …. the nonsence I come across on forums…. uninstall reinstall do the hokey pokey blah blah blah.. it is unbelievable. Anyway, thanks again.

  26. Using the resources below I had realised that the Image Capture program had the same problem as Vuescan – ie its an underlying network issue. The scanner simply doesnt work – 9923 error or 21345 – or nothing happens.

    I checked (as suggested) the IPv4 netwrok connection on the mac(s) and printer/scanner.

    The printer was working. The Network setting was IPv4 (not IPv6) so my problem was different from the experience of others in this thread – but I bet there are many who are having the problem uncovered below.

    I tried turning IPv6 on, and IPv4 off, for the printer.

    As you would know, IPv6 doesnt work, and I lost contact with the printer over the LAN. Unprintable words were spoken!

    I then started to reset the printer completely and its LAN settings (using the printer interface)

    This restored the printer with a new IP address on the LAN.

    Bingo! It worked with Image Capture and with Vuescan. We did the Hokey Cokey! 🙂

    I will give it another 24 hours to see if the settings fail again (this is how it began – one day fine, next day gone) and it stops scanning again. Fortunately this has taken only a few days not years!!

    Will let you know.

  27. Thanks and yes and it continues to work days later. The only blockage occurs when two computers or two programs attempt to talk to the scanner simultaneously – understandable! Wouldn’t have figured it out without your extensive resource and all those commenters – hopefully this helps someone else!

    1. Interesting. The two networks should come together at the router so it should not have mattered. But, you fixed it, so I’m happy for you. And I’ll remember this next time I do everything right and it still doesn’t work!

    1. System Preferences, then Network, then click on whichever kind of connection you have (it will have a green dot next to it), then click the Advanced…. button, then set IPv6 to “Automatically.” Then click OK, then click Apply. I’d probably restart the Mac also.

  28. Hi, Christian

    I tried both ways in my Mac and printer (HL-L2390DW), but it did not work. Then I saw your comments and download the Brother iPrint&Scan, then it worked. However, after scanning 3 pages, it stopped working again. Still shows “an error occurred while communicating with the scanner (-9923). Please help me. Thanks.

  29. Thanks so much for your reply. I did what you said and it still did not work. As I told you in another comment, I downloaded the iPrint & Scan and it worked. However, after scanning 3 pages, it stopped working again. Is there any other way to try? Thanks.

    1. When you made it work for three pages, and then it stopped, did it stay “stopped” forever? Or, after a restart, could you use the Brother spring & Scan app again (but only for three pages)?

  30. Thanks for your reply. Yes, after 3 pages, it stayed “stopped” forever and the notes ” an error occurred while communicating with the scanner.(-9923) appeared again. The only way I can make the scan right now is to download “Brother iPrint & Scan” and scan from there.

  31. Hi, There
    The ” Brother I print & Scan” stopped working finally. They asked to update and I did but failed. I was frustrated but no other way thanI trying your ways to change the printer setting and restarted the printer again, and it worked!!! Thank you so much!!!

  32. The easy fix worked…thank you. This is the first time I had that error, however my Mac and epson have been communicating poorly for awhile. I am hoping this fix might help this as well.

  33. I found your solution after hours scouring the internet and trying to figure out what the heck is up with my HP 9010 not connecting to my scanning app on the iMac. I am so HAPPY that this works. Thank you so much!!

  34. Thanks Christian, it works for me. Just one additional tip: once you changed the setting in your Mac, restart the machine and then it works perfectly.

  35. I’m sorry but everything in the network area on my Mac is grayed out. I can’t change anything without getting rid of that… how do I fix that?

    1. The left-hand side of the Network preference pane should show a few things (WiFi, Ethernet, maybe something else) and one of those things should have a green dot next to it. Click on that. Then, the right-hand side should have some options for you, and not be greyed out. Let me know–

  36. unbelievable – worked instantly! Thanks so much… been looking for a fix so many times, never found something that really worked, until now…. wow read through your posts – you need a reward for doing such a great a job… that HP or Mac should have done… Thanks. You saved my day…

  37. Thank you, Worked for me too. .
    Mine’s a cheapo epson )WF-2840 with rip-off cartridges!) Couldn’t find the location in it for turning off IPV6, accessed it via the inbuilt web APP

    So used the IPV6 set-up on my old Mac-Pro 5,1 – link-local only.
    I mention the age of the Mac just in case it might have a bearing but I cannot imagine what (probably find out soon enough when something else goes wrong)
    What puzzles me; I have just checked on my router and IPV6 is not enabled in my local network settings, the printer is connected via and IPV4 address
    Doubtless this all goes to prove my lack of knowledge re networking.

    Enjoy the ☕️

  38. I amthe most tech unsavvy person, really lazy about it, but this fixed the problem for me. Thank you so much! This still works : ))) You are the best!

  39. It’s late winter, 2024… and this is STILL a problem! And Christian’s solution still works! I had to turn off IPV6 at the printer; the settings were challenging to find on my Brother printer. Thank you Christian!

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