No 'Access-Control-Allow-Origin' header is present on the requested resource Django and ReactJS

Question

Currently I have Django 1.98 as Backend and React as Front End.

I'm getting this error:

Access to XMLHttpRequest at ' https://mywebsite:8000/uploads/vtt/ ' from origin ' http://localhost:3000 ' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.

I installed django-cors-headers==2.4.0 on my virtualenviroment

This is my settings.py file:

INSTALLED_APPS = [
    'django.contrib.admin',
    'django.contrib.auth',
    'django.contrib.contenttypes',
    'django.contrib.sessions',
    'django.contrib.messages',
    'django.contrib.staticfiles',
    'uploads.core',
    'corsheaders',
]

MIDDLEWARE_CLASSES = [
    'django.middleware.security.SecurityMiddleware',
    'django.contrib.sessions.middleware.SessionMiddleware',
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.common.CommonMiddleware',
    'django.middleware.csrf.CsrfViewMiddleware',
    'django.contrib.auth.middleware.AuthenticationMiddleware',
    'django.contrib.auth.middleware.SessionAuthenticationMiddleware',
    'django.contrib.messages.middleware.MessageMiddleware',
    'django.middleware.clickjacking.XFrameOptionsMiddleware',
]

CORS_ORIGIN_ALLOW_ALL = True

CSRF_TRUSTED_ORIGINS = ['http://127.0.0.1:3000','http://localhost:3000','http://localhost:8000','https://mywebsite:8000','https://myapp.firebaseapp.com','https://mywebsite:8088']
CSRF_COOKIE_NAME = "csrftoken"
CSRF_HEADER_NAME = [
    'HTTP_X_CSRFTOKEN'
]

SECURE_PROXY_SSL_HEADER = ('HTTP_X_FORWARDED_PROTO', 'https')
SECURE_SSL_REDIRECT = True
SESSION_COOKIE_SECURE = True
CSRF_COOKIE_SECURE = True

CORS_ORIGIN_WHITELIST = ['http://localhost:3000','https://mywebsite:8088']

CORS_ALLOW_METHODS = (
    'DELETE',
    'GET',
    'OPTIONS',
    'PATCH',
    'POST',
    'PUT',
)

CORS_ALLOW_HEADERS = (
    'accept',
    'accept-encoding',
    'authorization',
    'content-type',
    'dnt',
    'origin',
    'user-agent',
    'x-csrftoken',
    'x-requested-with',
)

Any idea how to solve it? Thanks.

Answer 1

Make sure https://mywebsite:8000/uploads/vtt/ is the correct URL.
In my case, I used the wrong port because my API used a different port.
I replaced 8000 with 52130 .

Answer 2

Try adding:

CORS_ORIGIN_WHITELIST = (
    'example.com',
    'localhost:3000',
    '127.0.0.1:3000',
    'more.domain.or.subdomains'
)

Don't forget add the middleware too

MIDDLEWARE = [  # Or MIDDLEWARE_CLASSES on Django < 1.10
    ...
    'corsheaders.middleware.CorsMiddleware',
    'django.middleware.common.CommonMiddleware',
    ...
]

Answer 3

django-cors-headers is reasonably fool-proof and your configuration seems correct to me.

There is however a gotcha I've had issues with too: Your uploads directory is likely not served through Django, but by the server directly as a static file (best practice and nearly default behaviour in Django). Even the built-in development server will serve static files without invoking your Django app.

Since your app is not invoked, django-cors-headers cannot apply a CORS header to those responses.

Answer 4

I had the same issue, and I think is a problem with:

SECURE_SSL_REDIRECT = True

I don't know the impacts over disabling it, but setting it to:

SECURE_SSL_REDIRECT = False

This make the cors problem gone.