HTTP 405 Method Not Allowed — What It Means and How to Handle It

As you build websites or integrate with APIs, you’ll encounter a variety of HTTP status codes. Most developers are familiar with 404 Not Found or 500 Internal Server Error. But another common and often confusing response is HTTP 405 Method Not Allowed.

This code doesn’t mean the resource is missing or the server is broken. Instead, it indicates something more precise about how the request was made.

In this article, we’ll explain what a 405 error is, why it happens, how it differs from other HTTP errors, and what you can do to prevent or fix it in your applications.

What Is HTTP 405 Method Not Allowed?

An HTTP 405 Method Not Allowed status code is a client-error response that indicates the server understands the request, but the HTTP method used (such as GET, POST, PUT, or DELETE) is not permitted for the requested resource.

Unlike a 404 Not Found, which means the URL doesn’t exist, a 405 error means the URL does exist, but the action you’re attempting isn’t allowed. The resource may only support specific HTTP methods.

Every 405 response should include an Allow header that lists which HTTP methods are permitted for the resource. This helps clients adjust their requests correctly.

How HTTP Methods Work

HTTP methods define the type of action a client wants to perform:

• GET fetches data from a server
• POST sends data to be processed
• PUT updates an existing resource
• DELETE removes a resource
• OPTIONS asks a server which methods a resource supports

When a request uses a method that the resource doesn’t support, the server returns a 405 error.

Common Scenarios That Trigger HTTP 405

Although the error focuses on request methods, several underlying issues can cause it:

Unsupported HTTP Method

The most common cause is using a method that the server does not support for that URL. For example, sending a POST request to a static HTML page or an endpoint that only accepts GET.

API Endpoint Restrictions

APIs usually define allowed methods per route. If an endpoint is designed only for GET requests, sending PUT or DELETE will result in a 405 response.

Misconfigured Routing or Server Rules

Web servers and application frameworks map URLs and methods to handlers. If routing rules do not include the method used, the request will be rejected.

Security or Firewall Rules

Some security configurations intentionally block certain HTTP methods to reduce attack surface, leading to 405 responses.

Incorrect CORS Preflight Handling

In browser-based requests, cross-origin calls trigger an OPTIONS preflight. If the server does not correctly handle OPTIONS, subsequent requests may fail with a 405.

How a 405 Error Appears

A typical 405 response looks like this:

HTTP/1.1 405 Method Not Allowed
Allow: GET, HEAD
Content-Type: text/html

In this example, the server indicates that the resource only supports GET and HEAD, so using other methods such as POST is not allowed.

How HTTP 405 Differs From Other Status Codes

Understanding similar status codes helps with debugging:

With a 405 error, the URL is correct — only the HTTP method is wrong.

Common Real-World Examples

You may encounter a 405 error in scenarios such as:

• A web form submits a POST request, but the server endpoint only supports GET
• A REST API route supports GET and PUT, but the client sends DELETE
• A browser sends an OPTIONS preflight request, but the server does not support OPTIONS

During API development, 405 errors are common when handler functions are defined for limited methods in frameworks like Express, Flask, Django, Rails, or Laravel.

How Developers Fix or Prevent HTTP 405 Errors

1. Verify the HTTP Method

Check API or endpoint documentation and confirm the method is supported. Review the Allow header in the response if available.

2. Update Routing Logic

Ensure that your server or framework routes explicitly handle the method you intend to use.

3. Handle Preflight Requests Properly

For cross-origin browser requests, make sure the server correctly responds to OPTIONS with allowed methods and CORS headers.

4. Check Server Configuration

Review configuration files such as .htaccess (Apache), nginx.conf (Nginx), or serverless routing rules for unintended method restrictions.

5. Debug API Permissions

For APIs using authentication or scoped permissions, confirm that the access layer supports the requested method to avoid confusion with authorization errors.

Why the Allow Header Matters

The Allow header is a critical part of a 405 response. It tells the client exactly which methods are supported, for example:

Allow: GET, HEAD, OPTIONS

This makes 405 errors more actionable than generic client errors.

Best Practices to Avoid 405 Issues

To minimize 405 errors:

• Match request methods to endpoint design
• Clearly document supported HTTP methods
• Follow REST conventions for method usage
• Define route handlers explicitly for each supported method

Consistent method usage and clear API design reduce unexpected 4xx errors.

Conclusion

The HTTP 405 Method Not Allowed status code indicates a method mismatch: the resource exists, but the request method is not permitted. Fixing it typically involves using the correct HTTP method, adjusting routing or server configuration, and handling preflight requests properly.

Understanding 405 errors helps developers build more predictable, robust APIs and web applications while reducing debugging time during development and integration.