Checkout Form Shows Data from Other Users

TL;DR
If your checkout form displays data from other users, the issue is likely caused by a caching plugin that is incorrectly caching pages generated for logged-in users. To fix this, ensure that your caching plugin excludes logged-in users from caching.

Cause

Most caching plugins are designed to improve performance by storing and serving static versions of pages. However, if a caching plugin mistakenly caches pages that were generated for logged-in users, the cached versions may contain pre-filled data that belongs to other users. When a logged-out visitor accesses these cached pages, they may see incorrect personal details, leading to a serious privacy issue.

Solution

To resolve this issue, follow these steps:

  1. Check Your Caching Plugin Settings
    • Navigate to the settings of your caching plugin.
    • Look for an option related to caching logged-in users.
    • Ensure that caching for logged-in users is disabled (most caching plugins disable this by default, but it may have been changed).
  2. Exclude WooCommerce Pages from Caching
    • Many caching plugins allow you to exclude specific pages.
    • Ensure that the pages with donation forms as well as checkout, cart, and account pages are excluded from caching to prevent data leakage.
  3. Clear the Cache
    • After making changes to your caching settings, clear the cache to remove any previously stored incorrect data.
    • Test the checkout process using an incognito/private browser window to verify that the issue is resolved.

Additional Considerations

  • If you are using a server-level caching solution (such as Varnish or Nginx FastCGI cache), check with your hosting provider to ensure proper configuration.
  • Some optimization plugins may also introduce aggressive caching; review their settings as well.
  • WooCommerce itself sets headers to prevent caching of sensitive pages, but some caching plugins may override these settings. Ensure that your plugin respects WooCommerce’s cache rules.

By following these steps, you can prevent checkout pages from displaying incorrect data and ensure a secure shopping experience for your customers.