Os x check for updates. Contacted Canon with a similar issue for my Canon MX870 and they suggested the following (which worked for me):
Software For Mac Computers
Hi had a look through the forum and cannot see anything that might help so have to ask for assistance. Just purchased a 5D Mk4 and loaded the latest EOS Utility 3, my macbook is running the latest version of macOS Mojave 10.14 but as soon as the camera is connected the EOS Utility crashes.
Canon's mac software is all 64-bit as long as you've been keeping up with updates. And it should be working fine. If not, make sure you update to the latest versions. MacOS Mojave wants everything to be 64-bit (although it is possible to run 32-bit. It is no longer recommended.).
Since there is no updated driver and software for your MX870, you can try downloading and installing the following Canon driver supplied by Apple. Since this is a third-party driver, Canon has not tested this and there's no assurance that it will work on your end.
Canon EOS R and EOS Utility 3 with macOS Mojave 10.14. I have read that many users can’t find the EOS Utility 3.9.0 download for the Canon EOS R while running macOS Mojave 10.14, the official Canon EOS R download list doesn’t show support for the latest Apple OS, but the software for the previous macOS software works just fine. Here are the direct links to download the software.
Printer and scanner drivers for Mac (OS X Lion or later)
Once installed, you can then use Image Capture to perform scanning. Mac logo.
1. Turn on or wake up your printer, but donÂ’t press any other buttons on it.
2. On your Mac, click on the Finder icon on your Dock.
3. Click on the Go menu, and then select Applications.
4. Locate and double click on Image Capture to open it.
5. On the left-hand side, youÂ’ll see two sections named Devices and Shared. Multifunction printers and scanners connected by USB cable will appear in the Devices section and networked or wireless devices will appear in the Shared section. (If your device isnÂ’t listed in either section, then it is not detected or itÂ’s likely not compatible with Image Capture.)
6. Click on your printer in either the Devices or Shared section to select it.
Eos Software Canon
7. You might need to wait while your machine warms up.
Canon Eos Utility Download Mac
8. Look at the picture below to see if your Image Capture looks similar. If not, click the Show Details button to expand the window so it looks like the image below. Click Scan.