LibreNMS Web UI does not load

I upgraded Ubuntu from 18.04 to 20.04 due the php alerts I was getting about it being out of date. After updating the Web UI does not load. and validate.php are both good. The error log is clean too.

Smells like php-fpm - follow through the install docs pretending like you’ve never seen them before and check that part closely.

There’s a well worn reference to another quick way here that may be relevant: Upgrading Ubuntu 20 to Ubuntu 22 and PHP 8.1 - #5 by murrant

I got further after finding a bunch a dependency errors now I am getting this error. Claims php is too old but validate.php shows otherwise.