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, it means 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’s different 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 HTTP request, but the HTTP method used (such as GET, POST, PUT, DELETE) is not permitted for the requested resource.

Unlike a 404 error, which means a URL doesn’t exist, a 405 error means the URL does exist, but the action you’re attempting isn’t allowed. The resource may be designed to respond only to specific methods.

Every 405 response must include an Allow header that lists which HTTP methods are allowed on the resource. This helps clients understand how to adjust their requests appropriately.

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

Even though the 405 error is about the request method, several underlying situations can lead to it:

Unsupported HTTP Method

The most common cause is simply using a method that the server does not support for that URL. For example, submitting a POST to a static HTML page or hitting an API endpoint that only accepts GET will result in a 405.

API Endpoint Restrictions

APIs typically define which methods are allowed per route. For example, an endpoint that returns user data may only support GET. Sending a PUT or POST will immediately trigger a 405.

Misconfigured Routing or Server Rules

Web servers and application frameworks map URLs and methods to handlers. If the routing configuration does not include support for a method you use, the request is refused.

Security or Firewall Rules

Some server security configurations or firewalls may deliberately block certain HTTP methods to reduce attack surface, leading to 405 responses when those methods are used.

Incorrect CORS Preflight Handling

In browsers, cross-origin requests trigger an OPTIONS preflight check. If the server doesn’t respond correctly to OPTIONS, subsequent methods may trigger a 405 error.

How a 405 Error Appears

A typical 405 response looks like this:

In this example, the server tells the client that the requested resource only supports GET and HEAD, so using other methods (e.g., POST) is not valid.

How HTTP 405 Differs From Other Status Codes

Understanding how 405 compares with similar error codes helps when debugging:

With a 405, you do have the right URL, but the HTTP verb (method) you used doesn’t match what the endpoint allows.

Common Real-World Examples

Here are typical situations where you might see a 405 error:

• A web form is set to send a POST, but the server endpoint was only configured to accept GET.
• A REST API route is defined only for GET and PUT, and the client sends a DELETE.
• Your browser sends an OPTIONS preflight request for a cross-origin API call, but the server doesn’t handle OPTIONS, resulting in 405.

Developers working with modern frameworks often encounter 405 errors during API development when handler functions are defined only for certain methods. Checking method support in frameworks like Express, Flask, Rails, Django, or Laravel is a common first step when debugging.

How Developers Fix or Prevent HTTP 405 Errors

Here are practical steps you can take to resolve a 405 error:

1. Verify the HTTP Method

Check the API or endpoint documentation to ensure you’re using a method supported by the resource. Review the Allow header returned in the error, if present.

2. Update Routing Logic

In your server or application framework, confirm that the route handler is configured to accept the method you intend to use, such as adding POST handling where appropriate.

3. Handle Preflight Requests Properly

If the request is coming from a browser in a cross-origin context, ensure the server responds to OPTIONS with appropriate allowed methods and CORS headers.

4. Check Server Configuration

Inspect server configuration files such as .htaccess (Apache), nginx.conf (Nginx), or routing settings in serverless platforms to make sure unwanted method restrictions are not applied.

5. Debug API Permissions

For APIs requiring authentication or scoped access rights, ensure that the authentication layer supports the method you’re trying to use. This won’t change the method support itself but can prevent misinterpretation of method errors.

Why the Allow Header Matters

A key aspect of the 405 response is the Allow header. This header tells the client exactly which methods the resource supports, for example:

Clients and developer tools can use this header to adapt requests, making the response more informative and actionable than a generic error.

Best Practices to Avoid 405 Issues

To reduce the likelihood of encountering 405 errors:

• Align your client request methods with the API or resource design.
• Document supported methods clearly in your API documentation.
• In REST APIs, follow conventional mappings (e.g., GET for retrieval, POST for creation, PUT/PATCH for updates, DELETE for deletion).
• Implement proper route definitions and method handlers in your server framework.

Following consistent conventions with method usage and endpoint definitions improves interoperability and reduces unexpected 4xx errors.

Conclusion

The HTTP 405 Method Not Allowed status code is a precise way for a server to communicate that a method mismatch occurred: the resource exists and the syntax is correct, but the method used isn’t permitted. You can fix it by using the correct HTTP methods, adjusting routing or server configuration, and ensuring proper handling of preflight and REST conventions.

Understanding 405 helps you build more robust web applications and APIs that respond predictably when clients make requests. It also helps developers diagnose and resolve issues faster during development and integration.