How to Resolve the Spring Boot '405 Method Not Allowed' Error

What are the common causes and solutions for the Spring Boot '405 Method Not Allowed' error?

The '405 Method Not Allowed' error in Spring Boot occurs when a client makes an HTTP request using a method that the server does not support for the specified resource. This is a common issue that can arise from several misconfigurations or incorrect method usage in your application.

@RestController
@RequestMapping("/api")
public class MyController {
    @GetMapping("/items")
    public ResponseEntity<List<Item>> getItems() {
        // Logic to retrieve items
    }

    @PostMapping("/items")
    public ResponseEntity<Item> createItem(@RequestBody Item item) {
        // Logic to create an item
    }
}

Causes

• The HTTP method used in the request is not mapped to any endpoint in the controller.
• Typographical errors in the request URL or incorrect endpoint definitions.
• Methods like POST, PUT, or DELETE are not correctly annotated in the Spring controller.

Solutions

• Ensure that the HTTP method used in the client request matches one defined in your Spring controller.
• Check your controller annotations to make sure you are using the correct mapping methods (e.g., @GetMapping, @PostMapping).
• Verify that the endpoint URL used in the request matches the URL specified in your Spring Boot application.

Mistake: Using the wrong HTTP method in the request (e.g., sending a POST request instead of GET).

Solution: Check the API documentation or controller definitions to ensure the correct method is used.

Mistake: Misconfigured request mappings due to typos or incorrect path definitions.

Solution: Review the endpoint URLs and method annotations in your controller to ensure they are correctly defined.