How to Fix HttpErrorResponse 405 Method Not Allowed When Connecting to Flask API via HTTPS Behind Nginx Reverse Proxy?

The "HttpErrorResponse 405 Method Not Allowed" error typically occurs when the client (your Angular frontend) is trying to perform an HTTP request method that is not allowed by the server (your Flask API). In this case, it seems like you are facing this issue when trying to connect via HTTPS. Here are steps to help you diagnose and fix the issue:

Step 1: Check Nginx Configuration

First, verify that your Nginx configuration is correctly set up to handle HTTPS requests. Ensure that you have an HTTPS server block in your Nginx configuration file (nginx.conf or a file in the /etc/nginx/sites-available/ directory). The server block should contain the necessary SSL configurations. Here is an example:

server {
    listen 443 ssl;

    ssl_certificate /etc/nginx/ssl/yourdomain.crt;
    ssl_certificate_key /etc/nginx/ssl/yourdomain.key;

    location / {
        proxy_pass http://localhost:5000;  # Adjust this to your Flask API address
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;

Make sure that the proxy_pass directive points to the correct address where your Flask server is running.

Step 2: Flask Configuration

Ensure that your Flask API is configured to accept HTTPS requests. In your Flask app, you can specify the host and port for the server like this:

if __name__ == "__main__":'', port=5000, ssl_context=('path_to_cert.crt', 'path_to_cert.key'))

Replace path_to_cert.crt and path_to_cert.key with the actual paths to your SSL certificate and private key files.

Step 3: Check Nginx Logs

Check Nginx error logs for any additional information. You can view the Nginx error log by running:

sudo tail -f /var/log/nginx/error.log

Look for any errors related to the HTTPS configuration or proxy pass.

Step 4: Test with Curl

You can use curl to test the connection from the command line. For example:

curl -k

This will help you determine if the issue is specific to your Angular frontend or if it's a server-side problem.

Step 5: Check CORS Settings

Ensure that you have configured CORS (Cross-Origin Resource Sharing) correctly in your Flask app if your Angular frontend is making requests from a different domain. Make sure the Flask server allows requests from your frontend domain.

Step 6: Check Angular Code

Verify that your Angular frontend is sending HTTPS requests to the correct URL. Ensure that the Angular code specifies the correct HTTPS URL when making API requests.

By following these steps and diagnosing the issue systematically, you should be able to pinpoint the problem and resolve the "HttpErrorResponse 405 Method Not Allowed" error when connecting via HTTPS.

Muhammad Alfaiz
Alfaiz 5 months ago
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