[PLUG-TALK] Downgrading "current" PHP or more

[Dick Steffens]

For quite a few years I've been running Apache, PHP and MySQL at home. 
It's mostly to provide a development platform for any sites I might 
deploy somewhere else. It's also where, up through Ubuntu 14.04, I've 
kept a copy of a site developed by someone else, but that I maintain. I 
don't use my 14.04 machine for day-to-day use anymore, and am slowly 
migrating stuff from it to my 16.04 machine in anticipation of upgrading 
to 18.04 in the spring or summer. In the last few days I've made a copy 
of all of the stuff on the 14.04's web folder and put it in the 
equivalent folder on 16.04. Most stuff works, but not the site I didn't 
write, but maintain. (Maintain is misleading. There's stuff I put on and 
take off, but it's not actually affecting any of the basic programming 
of the site.) When I visit that site on the 16.04 machine all I see is 
an image, but none of the text that comes from MySQL. I started noodling 
around and discovered I hadn't installed PHP. So, I did that, but ended 
up with PHP 7.0.22. On the 14.04 machine I have PHP 5.5.9. And I still 
just get an image without any text from the database.

I'm assuming there's something different about PHP 7 that's messing 
things up. Maybe it's how PHP 7 interacts with MySQL, but I don't know 
for sure. Since I didn't write the main code, and since that's the code 
that's running on Stablehost, I don't want to convert it to PHP 7.

Should I uninstall PHP, and maybe some other stuff (Apache? MySQL) and 
reinstall with older versions? Or is there a better way?

Thanks for whatever clue stick does the job.

-- 
Regards,

Dick Steffens