Nginx keeps adding the X-Frame-Options header to responses

Question

I created a widget to be shown on websites, it loads the Flask application that is running on AWS ElasticBeanstalk, nginx server. I can't make it work though, because nginx adds the following header to any responses:

sameorigin

I tried to add the following command to the config file:

add_header X-Frame-Options "" always;

But it didn't change anything. Then, I tried to add this command:

add_header X-Frame-Options "deny" always;

As result, I had the following error:

Refused to display 'https://xyz' in a frame because it set multiple 'X-Frame-Options' headers with conflicting values ('SAMEORIGIN, deny'). Falling back to 'deny'.

which means the header "sameorigin" is added anyway and I can't control it. How can I stop the server from adding this header?

The OS is "64bit Amazon Linux 2/3.5.2"

Answer 1

I was able to solve the problem with the changing config content to:

proxy_hide_header X-Frame-Options;
add_header X-Frame-Options "" always;