Need Software Update for iMac mid 2011

I am currently running Yosemite v. 10.10.5 and my computer says that there are no updates available.  I have tried to figure out how to install an older version on Photoshop but haven't had luck with that either! Any suggestions?

The last version of Photoshop to support macOS Yosemite was CC 2017... The links are here:

Adobe Creative Cloud 2017 Direct Download Links

"The CC 2017 release requires Mac OS X 10.10 (Yosemite) through 10.14 (Mojave)."

You have a ten year old computer running a long-unsupported version of OS X/macOS. As noted, you can upgrade to High Sierra but will still run into issues with Photoshop version requirements.

My suggestion is to start looking for a newer computer. I sold my mid-2011 iMac and bought a 2015 Retina 4K iMac used last year for under US$600, with 16GB of RAM and a quad-core i7. Great investment.

You can also get a new M1 Mac mini for well under $1000 (and Apple should be introducing new models any day.) M1 is the future and will be supported for several years down the line.

It’s weird that message came up all of a sudden.

Which version of Photoshop are you running?

There are two different upgrade tracks to look at here: Apple macOS, and Adobe Photoshop.

For macOS, the iMac specs on everymac.com say a mid-2011 Mac should be upgradeable as far as macOS 10.13 High Sierra. If Apple Software Update does not offer that to you, you can download the High Sierra installer yourself.

For Photoshop, you have a second challenge. Adobe now has a policy where the Adobe Creative Cloud desktop app (installer/updater) provides the current version and the previous version, but nothing before that. Right now, that means the Creative Cloud app can install Photoshop 2021 (version 22) or 2020 (version 21). The current version, Photoshop 2021, requires macOS 10.14 Mojave or later, which Apple does not support on a mid-2011 Mac, so you can’t install it even if you upgrade macOS on your iMac as far as it will go. You should be able to install Photoshop 2020, which requires macOS 10.13 High Sierra…the last version of macOS you can install on that iMac.

In short, you should be able to upgrade the iMac to macOS 10.13 High Sierra, and that would let you upgrade Photoshop to last year’s version 2020 (v21). And that is as far as that 10-year-old iMac will go.

How to understand this:

• Apple tends to support Macs for about seven years. After that, they start to drop support for them in macOS upgrades. That is why your iMac can’t be upgraded past macOS 10.13. 
• Adobe, as said above, provides only the current and previous versions of its applications. 

Your iMac is old enough that it’s unable to be upgraded to a version of macOS that’s supported by the latest version of Photoshop.

One final note: Although you shoudl be able to install Photoshop 2020 if the iMac is upgraded to macOS 10.13, if a new version of Photoshop is released this fall as has happened the last few years, Photoshop 2020 will be dropped and then no version will be available to be installed on that iMac.

After Adobe stops allowing installation of Photoshop 2020, its installer might be available from prodesigntools.com.