id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	uname	nginx_version
1818	Custom Error Pages fails to return the correct Content-Type header in its response	adrian.quiambao.torocloud.com@…		"Similar Issue with here: https://github.com/kubernetes/ingress-nginx/issues/4039

Background: I configured a custom error page on Nginx based on the Accept Header.

For example: curl -i https://test-nginx.text.com/api/nginxTest/502 --header 'Accept: application/json'. It would return on cli like this:

{{{
HTTP/1.1 502 Bad Gateway
Server: nginx
Date: Mon, 22 Jul 2019 00:16:13 GMT
Content-Type: application/json
Content-Length: 115
Connection: keep-alive
ETag: ""5d301e25-73""
X-Content-Type-Options: nosniff

{
  ""result"" : ""ERROR"",
  ""apiErrorCode"" : -1,
  ""message"" : ""Bad gateway"",
  ""localizedMessage"" : ""Bad gateway""
}
}}}

But if I didn't pass any Accept header. The default text/html should handle it. In cli, it shows the HTML error page but when I tried to access it on a browser the HTML error page would not show. 

In  Google Chrome v 75.0.3770.142 : It shows ""ERR_INVALID_SIGNED_EXCHANGE""
In Safari v 12.1: It would download the page
In Mozilla Firefox v63.0.3: It would show the custom XML custom error page
 
The code should return a default content-type header ''text/html'', but when it fails to decode the Accept header, it simply mirrors whatever came from the request into the response. 

The expected behavior, in this case, is for the default backend use Content-Type: text/html when it fails to decode the Accept header.

I already tried adding the add_header X-Content-Type-Options nosniff always, but it did not fix the issue.

Snippet custom nginx config:

{{{
map $http_accept $extension {
  default html;
  ~application/json json;
  ~application/xml xml;

      more_set_headers  'Content-Type:$http_accept';
}
}}}
"	defect	closed	blocker		nginx-module	1.12.x	invalid			Linux ip-10-1-200-10 4.9.119-44.140.amzn1.x86_64 #1 SMP Fri Aug 10 19:17:29 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux	"nginx version: nginx/1.12.1
built by gcc 4.8.5 20150623 (Red Hat 4.8.5-11) (GCC)
built with OpenSSL 1.0.2k-fips  26 Jan 2017
TLS SNI support enabled
configure arguments: --prefix=/etc/nginx --sbin-path=/usr/sbin/nginx --modules-path=/usr/lib64/nginx/modules --conf-path=/etc/nginx/nginx.conf --error-log-path=/var/log/nginx/error.log --http-log-path=/var/log/nginx/access.log --http-client-body-temp-path=/var/lib/nginx/tmp/client_body --http-proxy-temp-path=/var/lib/nginx/tmp/proxy --http-fastcgi-temp-path=/var/lib/nginx/tmp/fastcgi --http-uwsgi-temp-path=/var/lib/nginx/tmp/uwsgi --http-scgi-temp-path=/var/lib/nginx/tmp/scgi --pid-path=/var/run/nginx.pid --lock-path=/var/lock/subsys/nginx --user=nginx --group=nginx --with-ipv6 --with-http_ssl_module --with-http_v2_module --with-http_realip_module --with-http_addition_module --with-http_xslt_module=dynamic --with-http_image_filter_module=dynamic --with-http_geoip_module=dynamic --with-http_sub_module --with-http_dav_module --with-http_flv_module --with-http_mp4_module --with-http_gunzip_module --with-http_gzip_static_module --with-http_random_index_module --with-http_secure_link_module --with-http_degradation_module --with-http_slice_module --with-http_stub_status_module --with-http_perl_module=dynamic --with-http_auth_request_module --with-mail=dynamic --with-mail_ssl_module --with-pcre --with-pcre-jit --with-stream=dynamic --with-stream_ssl_module --with-google_perftools_module --with-debug --add-module=/datastore/temp/more_headers --with-compat --with-cc-opt='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector --param=ssp-buffer-size=4 -m64 -mtune=generic' --with-ld-opt=' -Wl,-E'"