If you can't install your Canon IP4900 IP4950 on Windows 10 or 7 etc, try this

When running Canon's installation or driver software (on disc or downloaded) If the printer dialogue box says either that the printer is supposedly detected (and you can see for yourself that it may be erroneously detected even when you plug a memory stick into the port) or even not detected during the Canon driver installation, and then of course in either case the installation fails, just go to your computer's Windows Device Manager and choose SOFTWARE DEVICES. If you see the printer listed there, just uninstall it by right-clicking UNINSTALL. I didn't reboot, but you can if you want to. Then run the Canon installation software again and the printer will probably install normally. This was the only solution that worked for me after days of trying different things. Nobody told me about it, I just know a little bit about how Windows works and wondered if it had muddled up what an IP4900 series is and somehow confused itself. I hope this helps someone.

PS I assure all readers I double-checked this before adding it as a solution and pressing Submit. If the above doesn't work, then perhaps someone else's solution will. But for me this was the only thing that worked after I tried dozens of other suggestions all over the internet.