Authentication is required, or the provided credentials are missing or invalid.
Quick facts
When does it occur
Authentication is required, or the provided credentials are missing or invalid.
It belongs to the 4xx Client Error class of responses, defined in RFC7235#6.3.1.
Browse all codes in this class: 4xx Client Error
How to fix it
Send the WWW-Authenticate header and verify that Authorization credentials are present and valid.
Common causes
How to fix it
Double-check the URL, return to the homepage and search again, or retry later.
Send the WWW-Authenticate header and verify that Authorization credentials are present and valid.
Review access logs and permission rules for the affected path, and confirm routing and security policies.
Frequently asked questions
401 belongs to the 4xx Client Error class and is generally not cached for long; behavior is controlled by Cache-Control.
4xx Client Error: Authentication is required, or the provided credentials are missing or invalid.
Sources & standards
Updated 2026-08-18
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