How to fix hsts disabled on Shopify Plus

Steps for Shopify Plus

1. Shopify Plus manages HSTS at the platform level for storefronts hosted on Shopify infrastructure — no manual header configuration is required or available in the admin.
2. For headless/custom storefronts or any reverse-proxy layer you control in front of Shopify Plus, add the Strict-Transport-Security header in your proxy/CDN configuration (e.g., Cloudflare, Fastly, or your own nginx/Node server).
3. In Cloudflare: Log in → select your domain → Security → Settings → enable HTTP Strict Transport Security (HSTS) → set Max Age to 12 months, tick includeSubDomains.
4. Verify with DevTools: F12 → Network → reload page → click the document request → Response Headers → look for Strict-Transport-Security: max-age=31536000; includeSubDomains.

What is hsts disabled?

HTTP Strict-Transport-Security (HSTS) is a security header your web server sends to browsers. It tells the browser: "Never load this site over plain HTTP — always use HTTPS, no matter what." Once a browser sees this instruction, it enforces HTTPS automatically for the duration you specify (the max-age, measured in seconds). A max-age=0 effectively disables HSTS, meaning the browser forgets the rule immediately and offers no protection. The correct setting is max-age=31536000 (one year) with includeSubDomains so all parts of your site are covered.

Without a valid HSTS header, shoppers who type your domain into a browser or click a plain HTTP link are briefly exposed to a "downgrade attack" — a hacker on the same network (e.g., public Wi-Fi) can intercept that first unencrypted request and silently redirect them to a fake version of your store, stealing passwords, credit card numbers, or session cookies. This is classified under OWASP's A02:2021 Cryptographic Failures, one of the most exploited vulnerability categories in real-world breaches. Beyond security, Google has used HTTPS as a ranking signal since 2014, and browsers display "Not Secure" warnings that destroy shopper trust and conversion rates. Fixing HSTS is a free, low-effort change with immediate security and trust benefits.

See the complete Hsts disabled guide for every platform and the full background.