Just figured out how to do php configuration for an addon domain where the installed script has been malfunctioning for a while. The answer seems obvious now, but that is what it means when my error_log file says this and that php code has been deprecated. Since the troublesome website rendering script is fairly old and I just globally updated my hosting’s php to run some more modern scripts, I needed to reset the php version for the specific domain back to a version that the old script was meant to work with. Duh!
How can I adjust the php settings specifically for an Addon Domain?
Configure PHP for an Addon Domain