https://www.junian.dev/tags/nginx/ Recent content in Nginx on Junian Dev Hugo -- gohugo.io en-us author@junian.dev (Junian Triajianto) author@junian.dev (Junian Triajianto) Copyright &copy; 2014 - 2026 Junian.dev https://www.junian.dev/dev/nginx-allow-underscore-header/ Sun, 28 Sep 2025 02:43:24 +0700 author@junian.dev (Junian Triajianto) https://www.junian.dev/dev/nginx-allow-underscore-header/ <p>Have you ever noticed that some HTTP request headers are missing when using Nginx?</p> <p>I experienced this issue myself. Headers containing underscores (such as <code>_Security_Token_</code> or <code>_Device_ID_</code>) were silently dropped by Nginx. This caused problems during mobile app testing, as token authentication kept failing.</p> <p>It turns out that HTTP headers with underscores are uncommon and generally discouraged when possible.</p> <p>The problem is, sometimes you don&rsquo;t have control over how the upstream server works.</p>