(blog.sucuri.net) Understanding and Resolving HTTP 401 Unauthorized Errors: Causes, Fixes, and Security Implications In brief - This article explains the meaning of the HTTP 401 Unauthorized response code and provides a comprehensive guide on how to diagnose and resolve it across various web environments. Technically - This article details the 401 status code as an authentication failure, distinguishing it from the 403 Forbidden code. It highlights the importance of the WWW-Authenticate header in identifying expected schemes like Basic or Bearer. The guide covers troubleshooting layers including browser cookies, server-level directives (.htaccess/Nginx auth_basic), reverse proxies that may strip Authorization headers, and WordPress-specific REST API requirements such as nonces and application passwords. Additionally, it addresses security implications where unexpected 401 spikes may indicate malicious code hooking authentication functions or unauthorized directory protection. Source: https://blog.sucuri.net/2026/10/http-401-unauthorized-what-it-means-and-how-to-fix-it.html #Cybersecurity