<p>My nginx-ingress-controller is in the <code>ingress-nginx</code> namespace and I've set the large-client-header-buffers to <code>4 16k</code>, <code>4 32k</code> etc.</p>

<pre><code>kind: ConfigMap
apiVersion: v1
metadata:
  name: nginx-configuration
  namespace: ingress-nginx  
data:
  proxy-buffer-size: "16k"
  large-client-header-buffers: "4 16k"
</code></pre>

<p>When I inspect the configuration in the nginx-controller pod I see:</p>

<pre><code> kubectl exec -n ingress-nginx nginx-ingress-controller-65fd579494-jptxh cat /etc/nginx/nginx.conf | grep large_client_header
        large_client_header_buffers     4 16k;
</code></pre>

<p>So everything seems to be configured correctly, still I get the error message <code>400 Bad Request
Request Header Or Cookie Too Large</code></p>

<p>There is <a href="https://github.com/kubernetes/ingress-nginx/issues/319" rel="nofollow noreferrer">dedicated topic on github</a> about the problem. You can find there possible solutions. This problem should be completely removed based on <a href="https://github.com/helm/charts/issues/20901" rel="nofollow noreferrer">this issue</a>.</p>
<p>Look also at more tutorials how can you solve this problem, but from the browser site:</p>
<ul>
<li><a href="https://www.minitool.com/news/request-header-or-cookie-too-large.html" rel="nofollow noreferrer">How to Fix the “Request Header Or Cookie Too Large” Issue [MiniTool News]</a></li>
<li><a href="https://support.mozilla.org/gl/questions/918154" rel="nofollow noreferrer">400 Bad Request Request Header Or Cookie Too Large nginx - What does this error mean?</a></li>
<li><a href="https://support.mozilla.org/en-US/questions/1327416" rel="nofollow noreferrer">HTTP Error 400. The size of the request headers is too long.</a>.</li>
</ul>
