🔍 Common and rare risks when modifying headers in .htaccess
🔴 Common problems
CSS and JS stop loading
If you misconfigure
Content-Security-Policy, you could block your own style and script files.
Solution: Make sure to include
'self'and other allowed domains inscript-srcandstyle-src.
Custom fonts don’t load
Blocking
font-srcin CSP can cause Google or other server fonts not to display.
Solution: Add
'self'and font domains tofont-src.
Broken images
Misconfigured
CORScan block images from loading from external servers.
Errors in APIs and connections to external services
If
Permissions-PolicyorCSPblock connections to external APIs, integrations like Google Maps or Facebook Login may fail.
🛑 Rare but possible risks
Website deindexing in Google
A misplaced
X-Robots-Tag: noindexin.htaccesscan cause Google to stop indexing your site.
Problems with WebSockets and real-time applications
Services like live chats or push notifications may be blocked if headers restrict
connect-src.
Conflicts with cache plugins
Some
Cache-Controlconfigurations in.htaccessmay conflict with plugins like WP Rocket or W3 Total Cache, affecting site speed.
Errors in older browsers
Some modern headers, like
Permissions-Policy, may not be recognized by older browsers and cause unexpected issues.
🚨 Why might payment gateways stop working?
Many payment gateways depend on external scripts and secure redirects. A bad header adjustment can block these functions, causing errors in the payment process.
🔴 Problematic headers for payment gateways:
Misconfigured Content-Security-Policy (CSP)
If it blocks scripts or iframes from external providers like Stripe, PayPal or Redsys, the gateway will not load.Example: A too restrictive CSP allowing only
'self'would block scripts fromstripe.com.
Solution: Include the necessary domains in
script-srcandframe-src.
Header always set Content-Security-Policy "default-src 'self'; script-src 'self' https://js.stripe.com; frame-src 'self' https://js.stripe.com"
Overly restrictive Referrer-Policy
Some gateways need to know from which page the user is coming to validate the transaction.
If you use
no-referrer, you could block this communication.Solution: Use
strict-origin-when-cross-origin.
Header always set Referrer-Policy "strict-origin-when-cross-origin"
X-Frame-Options with 'DENY'
If the payment gateway loads in an iframe, this header could block it.
Solution: Use
SAMEORIGINor allow the gateway domain.
Header always set X-Frame-Options "SAMEORIGIN"
🔧 How to avoid problems
✔ Make a backup before modifying .htaccess.
✔ Test in a staging environment before applying changes to production.
✔ Use tools like Security Headers and CSP Evaluator to verify your configuration.
✔ Check if your payment gateway has specific requirements about HTTP headers.