Update macOS for a mid 2011 intel iMac

The iMac (21.5-inch, Mid 2011) cannot run anything later than macOS 10.13.* (High Sierra).

High Sierra is eight major versions behind macOS 26 (Tahoe). It is far too old to run software from vendors such as Microsoft or Adobe. It is even too old to run the current versions of any major third-party browser, or of LibreOffice.

High Sierra is enough to run

• Firefox 115 ESR – an older version of Firefox that is still getting security updates from Mozilla (after having gotten many "stays of execution") (Mozilla Support – Firefox users on macOS 10.12, 10.13 and 10.14 moving to Extended Support Release)
• An old, archived, unsupported version of LibreOffice (The Document Foundation Wiki – Documentation/System Requirements)

But at this point, the main uses for such an old Mac are

• To run applications you already have
• To run 32-bit Intel applications, such as games, that won't run under Catalina and later
• To run PowerPC applications under Rosetta 1 translation, when started up under Snow Leopard (this particular Mac is old enough to run later releases of Snow Leopard)
• To access FireWire devices such as MiniDV and Digital8 camcorders

This type of iMac cannot be updated further then macOS 10.13 Catalina due to hardware limitations. It Is way too old to run any modern day macOS version

Sorry, but the built in hardware does not support any further macOS upgrades than 10.13.6

icarus_tsoi_boeing wrote:

(maybe up to macOS 12-17?)

P.S. – There is no macOS 17. Apple jumped straight from macOS 15.* (Sequoia) to macOS 26.* (Tahoe) when they changed the numbering schemes for all of their operating systems to model-year-based ones.