PHP 7.0 and MySQL start-up error “undefined symbol: mysqlnd_allocator in Unknown”

Question

Getting this warning on a custom-compiled version of PHP7, even when running php -v.

Tried all solutions posted. What could cause this?

Answer 1

(Posted on behalf of the OP).

Commands performed in order; I removed MySQL and PHP completely from system then:

sudo apt-get update
sudo apt-get install php7.0
sudo apt-get install php7.0-mysql

This seems to have fixed the error. Uuuugh.