400 error: request header or cookie too large for nginx

Question

Hello,

I am trying to run a website on elastic beanstalk. It's a node js / express app. I have uploaded the code to github, connected to it through code pipeline, then connected a beanstalk environment to the code pipeline. Also, I connected the custom domains `example.com` and `www.example.com` to the beanstalk environment through two `A` records in route 53.

When I click on the beanstalk domain `http://exampleapp-env.abc-123456.us-east-1.elasticbeanstalk.com/` it says `400 Bad request. Request header or cookie too large. nginx`. When I run `curl -I http://example.com` it says `Content-Length: 226`. This is also what it says in **F12**. I tried to look up the max request header size for nginx, and it said 4K - 8K ?

Also, I am creating a cookie in my `app.js` file with `response.cookie` but the `maxAge` is only `10000` which is only 10 seconds. Also this is the response, not the request ?

When I go to the EC2 instance that the beanstalk environment created and click on the public and private ipv4 addresses it just says `xx.xx.xx.xx took too long to respond.`

When I go to the actual domain `example.com` in the browser it also says `400 Bad request. Request header or cookie too large. nginx`.

Under **Configuration** > **Environment properties** I have an environment variable `PORT` with value `80` because according to [this article](https://docs.aws.amazon.com/elasticbeanstalk/latest/dg/create_deploy_nodejs_express.html) you should use 80. But I looked at the error logs in the beanstalk environment and under `/var/log/web.stdout.log` it says  `Error: listen EACCES: permission denied 0.0.0.0:80`.

Could someone please help me with this?

Accepted Answer

Hi, on your first point, Content-Length doesn't include cookies. See https://stackoverflow.com/questions/2773396/whats-the-content-length-field-in-http-header.

On max cookie size for Application Load Balancer, it's 16K.
See https://docs.aws.amazon.com/elasticloadbalancing/latest/application/sticky-sessions.html on sticky sessions

```
Since most browsers limit cookies to 4K in size, the load balancer shards 
application cookies greater than 4K into multiple cookies. Application 
Load Balancers support cookies up to 16K in size and can therefore create up to 4 shards that 
it sends to the client
```

Your error message says "Request header or cookie too large", so what is the content of your request sent when you click?

Best,

Didier

400 error: request header or cookie too large for nginx

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