Use an RFC 3339 date in the Expires line on Cloudflare

Why it matters

Expires must be a full date and time such as 2027-06-30T23:59:59Z, and a value that cannot be read is treated as missing. Tools then cannot tell whether the file is still current.

The fix

1. If the file is managed in Cloudflare, pick the date and time in the Expires at field under Security, Settings, Web application exploits, Security.txt, Configurations.
2. Save and reload the file to check the value.

Read the documentation ↗(opens in a new tab)

Related

• Reported by the security.txt check
• Publish a security.txt file
• Serve security.txt from /.well-known/
• Serve security.txt over https
• Serve security.txt as text/plain with utf-8
• Add a Contact line to security.txt
• Fix the Contact value in security.txt
• Add an Expires line to security.txt
• Renew the expired security.txt
• Renew security.txt before it expires
• Shorten the security.txt Expires date
• Fix repeated or insecure fields in security.txt
• Make the Canonical line match where the file is served