Older iMac

[OKBucks]

I've got a 27", mid-2010 iMac running High Sierra 10.13.6. I was in the process of installing a program but it popped up saying I need 10.15 or later.
It's been a minute since I've updated the OS, any help on a 10.15 version of High Sierra or am I topped out?
Thanks.

 

[MBAir2010]

High Sierra stops at 10.13 and 10.15 is Catalina which does not run on your iMac.
you could OCLP any os on that or ignore the program.

im using both Sonoma and Snow leopard now
while Catalina is on the stagnate MacBook Pro 2012.
if you need help opening or using that program im sure this can help install Catalina.

 

[OKBucks]

What is 'OCLP any os'?

Thanks for the link, I'll go through the info.

*Well it looks like a compatibility issue with the Radeon graphics acceleration in my computer. The info recommends not upgrading to Catalina due to the computer being mostly unusable if I do. The video mentioned a possible card upgrade of another part but I'm not sure what that is.

I seem to be SOOL.

*edited after reading the Catalina install info