Related to #20434, if you try to pull data such as CACHE from an environment variable and pass it to Twig, Twig's Bundle reads the type literally, as "false" or "true" - as it is passed from getenv.

How to Replicate

Add this environment variable:

CACHE false

In config.yml:

twig:
    cache: %env(CACHE)%

This results in a cache being created under web/false/, which is certainly not the intended result.

Note that this has other unintended consequences throughout Symfony, where a boolean is expected but not validated.

Solutions?

A simple solution could be to use the env() library created by Laravel as it provides for type coercion out of the box.