Forum Discussion
Altera used to have online access to all the old versions of software. You could download any version at any time.
For whatever reasons (trying to minimize support costs, I assume) Intel in 2020 IIRC deprecated a lot of legacy Altera software.
So MaxPlusII, Quartus, and a lot of other support software (eg, JAM STAPL Player source) were all taken offline, and no longer available.
So those engineers tasked with supporting old legacy designs are sometimes going to be SOL.
I have always made it a habit of, when starting a new design with some vendors software, of making archive copies of all required installation files, including specific versions of Windows OS software, if required. So in your case I would just pull out the Quartus 15.1 install media and install on a new system and be ready to go.
But if you are a new designer tasked with taking over a legacy project with the original designers long gone, that may not be an option.
There is no good answer. Intel has made a business decision that support of legacy designs does not matter to them.