Additional php versions and open_basedir
In default the open_basedir of a site points to the system-library of php.
When using a additional php version this one should be replaced with the library of this version. Eg, /usr/share/php5:/usr/share/php:
should be replaced with /opt/php-7.1/lib/php
(or whatever this version is installed).
This means: when activating a new php-version in config is a field missing for the open_basedir
restrictions of this version.
This moment a admin has to fix the oben_basedir entry of website when switching the php-version.