Troubleshoot TemplateNotFound error from Flask under Gunicorn

Question

I\'ve got a Flask app that I\'m trying to deploy using Gunicorn and nginx. However, although it works fine locally, it throws a TemplateNotFound error when I run in with Gunicor

Answer 1

Today, I experienced identical problems after a long period of my Flask app behaving quite normally (ie not throwing TemplateNotFound exceptions). None of the approaches mentioned by others here hit the mark or seemed appropriate (eg app.debug, path manipulation).

Instead, I tracked it down to the standard Flask app initialisation line:

app = Flask(__name__)

I had changed __name__ to another value (to get access to a named logger), not expecting for all this carnage to unfold :-) Don't change this value unless you are very familiar with Flask internals.