What is the latest OS I can upgrade to if my iMac is a mid 2010?

Hi there!

While macOS High Sierra is the latest version of macOS compatible with your Mac, you may be able to connect to your HP printer using Apple AirPrint if it supports it. This Apple article should help with that: About AirPrint - Apple Support.

-Jack

Hi,

Yes, as has been mentioned, macOS 10.13 High Sierra would be the maximum operating system for a mid-2010 iMac.

HP Smart for Desktop would today need macOS 10.15 Catalina. Is this the app you are referring to?

Let us see if there could be a way around this problem.

Which exact HP printer model do you have?

An AirPrint-compatible printer should in principle be able to work with an operating system as low as Mac OS X 10.7 Lion, but a printer manufacturer may provide extra software (necessary or not) for setup, ink management or similar purposes with higher requirements.

AirPrint per se would not need additional drivers, and should work with macOS 10.13 High Sierra if the printer and your Mac computer are connected to the same network (Wi-Fi router). AirPrint works with wireless (Wi-Fi) or wired (Ethernet) network connections.

Often, one can use a manual setup method, thus eliminating any need for special (setup) software. It may be somewhat more complicated if an ink subscription agreement is involved, but an iOS/iPadOS version of an HP Smart app could possibly be used as a workaround for certain operations if absolutely necessary.

About AirPrint - Apple Support

A mid-2010 iMac cannot run any version of macOS later than High Sierra.

You may want to consider installing Firefox 115 ESR . Mozilla no longer provides new features for High Sierra users, but this version of Firefox is more recent than the version of Safari in High Sierra.