405 Method Not Allowed Explained
What happens when a verb is not permitted.
405 Method Not Allowed Explained is a free Flask Academy lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Flask Academy learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What 405 Means
A 405 Method Not Allowed response means the URL exists, but the verb you used is not permitted on it.
405 Is Not 404
Do not confuse the two. A 404 means the path was not found, while a 405 means the path is real but rejects that verb.
How Flask Triggers It
If a route lists only POST and a client sends GET, Flask returns 405 automatically before your view ever runs.
@app.route("/save", methods=["POST"])
def save():
return "ok"The Allow Header
A well-formed 405 includes an Allow header listing the verbs the route does accept, so clients learn what to use instead.
It Is a Client Error
Codes in the 4xx range blame the request, not the server. A 405 says the client picked the wrong method for that endpoint.
A Common Cause
Submitting a form whose route forgot to allow POST is the classic trigger. Add POST to the methods list to fix it.
Browser Versus Form
Typing a URL sends a GET. If that route only allows POST, the browser shows a 405 instead of your page.
Customize the 405 Page
Give clients a friendlier reply by registering an errorhandler for 405 that returns your own message or JSON.
@app.errorhandler(405)
def bad_method(e):
return {"error": "method not allowed"}, 405Return JSON for APIs
For an API, a 405 should still speak JSON. A handler keeps your error shape consistent with every other response.
Read the Allow Header
When debugging, inspect the response's Allow header. It tells you exactly which verbs the route was declared to accept.
Fix It at the Route
The real fix is almost always in the methods list. Add the verb you need rather than working around the 405 elsewhere.
Quick Check
Tell 405 apart from its neighbor.
Recap
A 405 means a valid URL with a disallowed verb, unlike a 404. Read the Allow header and fix it by updating the methods list. Well done! 🎯
Frequently asked questions
Is the “405 Method Not Allowed Explained” lesson free?
Yes — the full text of “405 Method Not Allowed Explained” is free to read here on the web, and the Flask Academy course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Flask Academy course, upgrade to CoddyKit PRO.
What will I learn in “405 Method Not Allowed Explained”?
What happens when a verb is not permitted. You practise Flask Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Flask Academy?
No prior experience is required. Flask Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “405 Method Not Allowed Explained” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Flask Academy lesson?
Yes. Every Flask Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Declare Allowed Methods on a Route
- Branch Logic by request.method
- Read POST Data from the Body
- 405 Method Not Allowed Explained