Moving Drupal 7 site to Ubuntu 16.04

When I’ve moved a website as is from Ubuntu 12 to 16 it gave many problems to me.

I’ve upgraded to latest 7.x version but still problems.

However there is another 7.x site and is somehow working ok. Gave some problems then I ran drush updb  and since then seems to be running fine.

So what is the way to run existing 7.x to run on Ubuntu 16?

Drupal version: 


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