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

I have just spent 2 hours in a very similar situation and thought I'd post what ended up being the solution.

I was suddenly getting TemplateNotFound errors in the Apache logs from my Flask application, in production, which had been running fine until then. This resulted in 500 errors across the site.

First issue was that the TemplateNotFound errors did not show unless I had Flask's "debug" flag on -- there was no sign of any problems at all in the Apache log despite LogLevel set to info.

Running the app "locally" (Flask listens on localhost:5000) was fine (one can test the pages via wget 127.0.0.0:5000). It turned out that a copy of the main web app python code had somehow landed in the directory above where it should have been. This was imported by wsgi first and, as a result, the relative path to templates was incorrect.