How to keep my Adobe CS6 on Mojave - on my Mac

I have Photoshop CS6, Lightroom 6.14, QuickTime Player Pro 7, MPEG Streamclip etc old 32-bit apps on an external Mojave APFS volume. I occasionally Option-boot Mac mini 2018 to it from Sequoia which is on the internal disk. Carbon Copy Cloner can make a bootable clone with its "legacy" option even from Sequoia (but silicon Macs might be picky about this).

Options…

Figure out what you’re going to replace Adobe Creative Cloud CS6 with. There are some fine choices alternatives for various parts of the Adobe Creative Cloud suite, too. Which depending on which parts of CS6 you’re most using.

As for external boot, here’s how: Use an external SSD as your startup disk … - Apple Community

You can install and boot macOS 10.14 as a guest of a virtual machine on a newer macOS version on this or on another Intel Mac.

You can also use a browser with longer-term support that’ll run further back.

Careful.

Photoshop CS6 has DRM that requires you to "activate" with an Adobe server. If the following threads are accurate, Adobe shut down the DRM activation servers for CS6 some time ago. That implies that, if you do a "clean reinstall" of CS6 now, you will not be able to get it to work again.

How to activate Adobe photoshop CS6 on hi… - Apple Community

https://community.adobe.com/t5/photoshop-ecosystem-discussions/cs6-no-longer-functions/td-p/14861146

Servant of Cats wrote:

Careful.

Photoshop CS6 has DRM that requires you to "activate" with an Adobe server. If the following threads are accurate, Adobe shut down the DRM activation servers for CS6 some time ago. That implies that, if you do a "clean reinstall" of CS6 now, you will not be able to get it to work again.

There is similar risk when you clone CS6 to another drive because doing so changes the hardware setup. That's why I suggested that the OP clone the internal Mojave drive to his/her external drive and then test to make sure CS6 still works from the external drive (that is, booted from the external AND running CS6 from the external).

Adobe has indicated there is a new method for activating older versions of Creative Suite:

• https://community.adobe.com/t5/download-install-discussions/signing-into-and-activating-legacy-adobe-applications/td-p/14372541 and
• https://helpx.adobe.com/x-productkb/global/reactivate-older-apps.html

CarbonCopyCloner will work to clone a Mojave drive to an external drive (SSD or HDD). I suggest doing the clone then make sure it works to your satisfaction.

One of the potential problems may be the licensing permissions of the copy of CS6 on the external drive. If it doesn't work on the external drive then your alternative is to keep Mojave & CS6 on the internal drive and install Monterey on the external drive. The Late 2013 Mac Pro can be upgraded to Monterey.

Do note that your 2013 Mac Pro has Thunderbolt 2 & USB 3.0 ports. You may have difficulty finding an external TB2 drive these days, so USB 3.0 may be your only reasonable choice. One more thing, do not use a USB 4 drive unless the specs for the drive indicate that it also supports USB 3.0! USB4 is not backward compatible.

It very much depends on whether or not you have the 64 bit version of the Adobe apps. I have Photoshop CS6 64-bit and while I'm aware that any 32-bit plug-ins won't work from Catalina onwards, you shouldn't worry about the basic program. However, if you have the 32-bit version of the software, you can't get it past Mojave - that's simply a fact of life; but if you're running a more recent OS on an Intel Mac, you could use a virtual machine with Mojave installed in it in order to run Adobe 32-bit.

An external USB 3.0 drive will work just fine as an external boot (system) disk. And in general operation you probably won't see much difference between booting off the external vs. the internal.

You may see some difference between an external HDD vs. an SSD. A good external SSD may prove slightly faster overall than an HDD because the SSD will nearly always operate at full speed whereas an HDD, even at 7200 rpm, will have variable performance depending on head movement especially as the drive fills up. But both will ultimately be limited by the Mac Pro's 5 Gbps USB 3.0 interface.