Electronics

[gardenman]

The obvious thing is to check and be sure the printer is turned on. (I know, any idiot knows that, but sometimes the obvious things are easiest to overlook.)

I have this ridiculous Blu-Ray player that drove me nuts when I first got it as the power light lights up only when the power is off. Turn it on and there's no sign it's on. Turn it off and the power light comes on. For longer than I like to think about, I was turning it off, thinking I was turning it on and then confused why it wasn't working. Eventually I tried using it while it was "off" (no light) and miracle of miracles, it worked! (In my defense I'm one of those rare idiots who actually reads the owner's manual and the manual specified that the power light would come on when the player was on. I foolishly believed them.)

If the printer is turned on and still functional then the problem lies elsewhere. If a different USB port doesn't help then you could be in trouble. I don't know if you've updated your OS lately, but if you have, it's posible the new OS isn't compatible with your current printer. If there's a new updated driver available that might solve the problem. If it's an older printer, then getting an updated driver could be impossilbe.

[Zhills]

I have a PC but I have this happen when my computer was "updated" by Microsoft.  Once I had to uninstall and reinstall the printer.  I know you have an Apple but they are not that different.

[last mango]

I have a Canon printer and I used to get that message.  I remember something about having to select “network” when setting it up but I can’t remember the specifics.  I will see if i can find something on the web.  Here is what someone suggested: 

Thanks everyone for suggestions. Here's what worked: powered down printer, iMac, laptops; reset router; brought printer online with router; restarted iMac and magically it found ALL wireless printers in the house. Laptops were brought online and also found ALL wireless printers.

try this out and see if it works.  

[last mango]

Ok I found this - it is a bit long- but read it a few times and follow what they did where it is bold typed.  They had an Mg800 printer - whatever that is— but sub in your printer for that.  Also be sure to choose canon IJ network when that is a selection- I think that is what tripped me up when this happened.  

These are the steps:
Go to canon.com/usa OR usa.canon.com (the 1st link takes you to usa.canon.com)
In the search field, enter MG6821 - this will bring you to the Downloads & Drivers page for this printer
When I got to this page, it detected my OS - Mac OS X El Capitan 10.11.1
FIRST download MG6800 series CUPS Printer Driver Ver 13.6.0.0 (OS X) - this is the Canon IJ Printer Driver
After the .dmg file is downloaded, click to open and install
SECOND download ICE Driver Ver. 4.1.2 (OS X) - this is a scanner driver for this printer
After the .dmg file is downloaded, click to open and install
ON THE PRINTER ITSELF, go to the screen and select LAN settings --> Wireless LAN setup --> Standard setup
You will get Searching for wireless router
In my case, my guest LAN was found
Select the LAN and follow the prompts to enter the password - after this, my printer was on my guest LAN
Back to your computer: System Preferences --> Printers and Scanners
Click on the plus sign (+) to add the printer
Wait a bit -- the first MG6800 printer that comes up in the list is Multitask Bonjour - you do not want this one. Also, do not select the MG6800 that is listed under Nearby printers -- you won't get the correct one, which is Canon IJNetwork
The 2nd one that comes up in the list is the one you want - it says Canon IJNetwork
Select Canon IJNetwork to add it to your network - at this point, the printer, your computer, and your LAN should be coexisting in harmony with each other
THIRD download IJ Scan Utility Verx. 2.1.6 (OS X) - this is optional, but I have already used it, and it works nicely for "easy" scans
After the .dmg file is downloaded, click to open and install
Do a test print and test scan