Common Problems

HTTPS issue

By default, Jet Bridge will run in HTTP mode while Jet Admin opens in HTTPS. This can lead to a similar error when trying to connect to Jet Bridge running under HTTP:

Mixed Content: The page at 'https://app.jetadmin.io/builder/...' was loaded over HTTPS, but requested an insecure XMLHttpRequest endpoint 'http://JET_BRIDGE_HOST/api/discover/connection/'. This request has been blocked; the content must be served over HTTPS.

You have several options how to fix this issue:

1. Run Jet Bridge in HTTPS mode using SSL_CERT and SSL_KEY options (see Configuration). You will need an SSL certificate and private key for the domain name under which Jet Bridge is running. If you don't have an SSL certificate you can create self-signed SSL certificate files .crt and .key (Manual).

2. Run Jet Bridge behind a web server with HTTPS configured (for example nginx).

3. (for Test purposes) You can use Jet Admin in HTTP mode. We allow you to open your App in HTTP mode if you change HTTPS to HTTP in your browser URL. Be sure to connect to Jet Bridge with http:// on your browser URL otherwise, you will get a connection error.

For testing, you can use Ngrok service to put your application on the internet via HTTPS

CORS issue

If you are deploying Jet Bridge behind a proxy or some webserver you can start receiving the following errors in your browser console:

Access to XMLHttpRequest at '...' from origin 'https://app.jetad.io.io' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Normally you shouldn't have this issue as Jet Bridge automatically adds the appropriate CORS headers to all responses.

Behind Nginx

To fix the CORS issue for Nginx add the following to jetbridge.yourdomain.com.conf:

my-website.conf

server {
    listen 80;

    server_name jetbridge.yourdomain.com;

    return 301 https://$host$request_uri;
}

 server {
      listen 443 http2 ssl;
      ssl_certificate /etc/nginx/ssl/yourdomain.com.crt;
      ssl_certificate_key /etc/nginx/ssl/yourdomain.com.key;
      server_name jetbridge.yourdomain.com; 

    location / {
      ###################################
      # START
      # Add this block to your location
      ###################################
      
      proxy_hide_header 'Access-Control-Allow-Origin';
      proxy_hide_header 'Access-Control-Allow-Methods';
      proxy_hide_header 'Access-Control-Allow-Headers';
      proxy_hide_header 'Access-Control-Expose-Headers';

      if ($request_method = 'OPTIONS') {
        add_header 'Access-Control-Allow-Origin' '*' always;
        add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, PATCH, DELETE, OPTIONS';
        add_header 'Access-Control-Allow-Headers' 'Authorization,DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
        add_header 'Access-Control-Max-Age' 1728000;
        add_header 'Content-Type' 'text/plain; charset=utf-8';
        add_header 'Content-Length' 0;
        return 204;
      }

      add_header 'Access-Control-Allow-Origin' '*' always;
      add_header 'Access-Control-Allow-Methods' 'GET, POST, PUT, PATCH, DELETE, OPTIONS';
      add_header 'Access-Control-Allow-Headers' 'Authorization,DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range';
      add_header 'Access-Control-Expose-Headers' 'Content-Length,Content-Range';
      
      ###################################
      # END
      ###################################
      
      proxy_pass http://127.0.0.1:8888; # default port for jet-bridge
    }
}

If you don't have a certificate for https you can use Let’s Encrypt. A free and open Certificate Authority (CA), provides an easy and automated way to obtain SSL certificates.

To install Certbot, follow these steps:

#For Ubuntu/Debian:
sudo apt-get update
sudo apt-get install certbot

#For CentOS/RHEL:
sudo yum install certbot

#To obtain a Let’s Encrypt SSL certificate for your domain, run the following Certbot command:
sudo certbot certonly --nginx -d yourdomain.com

#If successful, the certificate and private key will be stored in /etc/letsencrypt/live/yourdomain.com/

#make the following changes in jetbridge.yourdomain.com.conf:
    ---
      ssl_certificate /etc/nginx/ssl/yourdomain.com.crt; -> ssl_certificate /etc/letsencrypt/live/yourdomain.com/fullchain.pem;
      ssl_certificate_key /etc/nginx/ssl/yourdomain.com.key; -> ssl_certificate_key; /etc/letsencrypt/live/yourdomain.com/privkey.pem;
    ---
    
#Let’s Encrypt certificates have a validity of 90 days. To ensure uninterrupted SSL protection, automating the certificate renewal process is essential. Certbot provides a renew command that you can schedule to run periodically.

#To add a renewal cron job, open the crontab editor:
sudo crontab -e

#Add the following line to run the renewal check daily:
0 0 * * * certbot renew --nginx --quiet

This is because newer versions of the Pillow Python library are incompatible with Python 3.4 or lower. Install an older version to fix this error:

pip install pillow==4.3.0

[Python 3.4 or lower] Error when running Jet Bridge: AttributeError: 'module' object has no attribute 'module_from_spec'

This is because newer versions of the date parser Python library are incompatible with Python 3.4 or lower. Install an older version to fix this error:

pip install dateparser==0.7.1

[Django] Fields generated by django-modeltranslation package does not displaying and saving correctly

The problem is that django-modeltranslation patches Django models so you need to load jet_django package only after django-modeltranslation has finished its patching this way in your settings.py:

INSTALLED_APPS = (
    ...
    'modeltranslation',
    'jet_django', # load after modeltranslation
    ...
)