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"NS_ERROR_NET_INADEQUATE_SECURITY" error when accessing Kiwi NG

When attempting to access Kiwi Syslog Server NG using HTTPS on https://localhost:5000, the browser throws the error: NS_ERROR_NET_INADEQUATE_SECURITY This error prevents the web GUI from loading over a secure connection.

First published date

8/22/2025 7:54 AM

Last published date

8/22/2025 3:32 PM

Overview

This issue occurs in environments with strict security policies, especially when HTTP/2 is enabled by default in modern browsers (e.g., Firefox). If the server does not support acceptable ciphers or TLS settings, the connection is rejected.

This is a client-side security enforcement, meaning the browser refuses to establish a connection it considers insecure — even if the server is technically reachable.

Product section

Kiwi Syslog Server

Cause

The error is caused by inadequate or deprecated cipher suites on the server side that are not compliant with HTTP/2 requirements.

Specifically:

  • Browsers (especially Firefox and Chromium-based) enforce strict cipher requirements for HTTP/2.

  • If the server is restricted to old or weak cipher suites (e.g., due to Group Policy, hardening guides, or manual configuration), the browser will block the connection and show the NS_ERROR_NET_INADEQUATE_SECURITY error.

Resolution

Update Cipher Suites on the Server

Ensure that the server supports modern TLS 1.3 cipher suites that are compatible with HTTP/2. Recommended cipher suites include:

  • TLS_AES_256_GCM_SHA384

  • TLS_AES_128_GCM_SHA256