Hello, my name is ***** ***** I will do my best to assist you with your Canon printer.
The reason you are receiving error 2112 is because the paper settings on the printer differ from the paper that is in the tray.
Please click on this link for troubleshooting this issue:http://ugp01.c-ij.com/ij/webmanual/ErrorCode/MG7700%20series/EN/ERR/2112.html
There are a few steps and suggestions to help you out.
Please let me know if you still require assistance.