I am using create react app to bootstrap my app.
I have added two .env files .env.development and .env.production in the root.
.env
.env.development
.env.production
And remember not to have semi-colon after the API key in the env-file.
REACT_APP_API_KEY = 'ae87cec695cc4heheh639d06c9274a';
should be
REACT_APP_API_KEY = 'ae87cec695cc44heheh1639d06c9274a'
that was my error