Troubleshooting WooCommerce: Steps to Resolve Cart Persistence Issues

Troubleshooting WooCommerce is going to be complex, since there is so much to WooCommerce. Even limiting to “Cart and Checkout”, there are potential problems at several levels, including the database, WordPress core, plugins, payment processors, site security, information privacy, and more.

1. Environment Consistency Check:
   • Confirming that the staging and production environments are identical (including PHP version, MySQL version, server configurations, and WordPress version) is crucial for accurate troubleshooting. Make sure there are no discrepancies.
   • If possible, clone the live site to a staging environment on the exact same server to replicate the environment as closely as possible.
2. Database Synchronization:
   • Ensure that the staging database is a recent clone of the production database. This will help in reproducing the issue if it’s data-related.
3. Error Logging:
   • Ensure that WP_DEBUG, WP_DEBUG_LOG, and WP_DEBUG_DISPLAY are configured correctly to capture any errors, warnings, or notices. Check the debug.log file, and the PHP error log, for any relevant entries that might indicate what’s going wrong.
   • See Debugging in WordPress – Documentation for these settings and where to set them.
4. Cache Validation:
   • Although you’ve disabled caching at various levels, ensure that there’s no server-level caching or other caching mechanisms at play which could be causing discrepancies between environments.
5. Transients:
   • Clearing transients is a good step. Corrupted or stale transients can cause unexpected behavior.
   • Transients are meant to be short term, to minimize complex database queries. So, (unless the plugin has bugs such as not using transients properly) you should be able to delete any transient at any time. If you have command line, wp transient delete --all or there are MySQL queries to delete them.
   • Transient Cleaner By David Artiss
6. Plugin Conflict Test:
   • Although risky on a live site, disabling other plugins temporarily or doing a binary isolation (disabling half the plugins, then half of the remaining half, etc.) could help identify a conflicting plugin.
7. Theme Conflict Test:
   • Temporarily switch to a default WordPress theme (currently Twenty Twenty-Three, or Twenty Twenty-Four is about to be released) to see if the issue persists. If the issue resolves, it could be a theme-related problem.
8. Custom Code Review:
   • Review the custom functions you have written (if any) related to cart persistence to ensure they are coded correctly and are compatible with the live site’s environment.
   • Must pay attention to security, privacy, transients. Plus, you have to not conflict with parameters or settings of the main plugin.
   • Minimize your custom code as it requires a lot of testing and maintenance, every time the main plugin is updated.
9. WooCommerce Configuration and Version Check:
   • Ensure that WooCommerce settings related to cart and sessions are correctly configured.
   • Check that the WooCommerce version on the live site is the same as on the staging and dev sites.
10. Server Configuration Check:
    • Check server configurations for session handling and other server-level settings that might affect cart behavior.
11. External Services:
    • Temporarily remove CDN such as Cloudflare from the equation by updating the DNS to point directly to the server, ensuring any changes have fully propagated. This can be risky due to potential downtime, but it could help rule out CDN caching as the culprit.
12. Monitoring and Logging Tools:
    • Utilize monitoring and logging tools to observe the behavior of the cart during the login process to see if there’s any noticeable difference between environments. Debugging in WordPress (link above) suggests some.
13. Support Channels:
    • Reach out to hosting support to see if they have any insights or if they can replicate the issue on their end.
    • Reach out to WooCommerce support or community forums with the detailed information about the issue to get more insights.

Given the precarious nature of the live environment, some of these steps may come with risks or may not be viable. Each action should be weighed carefully against the potential impact on the live site. Taking a systematic, well-documented approach to troubleshooting will hopefully help isolate and resolve the issue with the least amount of disruption.

Caches to Disable for Troubleshooting

When debugging WooCommerce issues, it’s crucial to disable caches to ensure that you are seeing real-time, accurate results. Here are some of the key caches and caching layers to consider disabling:

1. Browser Cache:
   • Your web browser stores static files to load pages faster. Make sure to disable browser caching or use incognito/private browsing mode to prevent old data from being displayed.
   • Many browsers have a right-click Inspector and on the Network tab there is a check-box to toggle the browser cache on/off.
2. Page Caching:
   • Page caching is often managed by plugins or server configurations. This type of caching stores static HTML copies of your pages to serve to users, bypassing the need to generate the page from PHP and database queries, for every visitor.
3. Object Caching:
   • This type of cache stores database queries or other objects to reduce the load on your database and speed up page loading times.
4. Database Cache:
   • Some hosting platforms or plugins provide database caching to speed up database query times. Make sure to flush or disable this cache to ensure you’re seeing up-to-date data.
5. CDN (Content Delivery Network) Caching:
   • CDNs like Cloudflare cache static content across their network to reduce loading times. Disable CDN caching or put it in development mode to prevent old content from being served.
   • WooCommerce pages like the shopping cart and the checkout pages should never be cached. That information must be private and current. Make sure all plugins you use, know how to prevent these pages ever getting cached.
6. OPcache:
   • PHP’s OPcache speeds up PHP by storing bytecode in memory, preventing the need to re-compile PHP scripts on each request. Resetting or disabling OPcache might be necessary for debugging.
7. Varnish Cache:
   • If your server or hosting provider uses Varnish, ensure it’s disabled. Varnish is a powerful HTTP cache that can mask issues.
8. Server-Level Caching:
   • Check with your hosting provider to see if there’s any server-level caching enabled and if so, request to temporarily disable it while debugging.
9. Transient Caching:
   • WordPress transients are used to store cached data temporarily. While not a traditional cache, corrupted or outdated transients can cause issues.
10. Full Page Caching Plugins:
    • If you are using any full page caching plugins, ensure that these are deactivated during the debugging process.
11. Asset Optimization Plugins:
    • Plugins that minify or concatenate CSS and JavaScript files also have a sort of caching mechanism. Ensure these plugins are deactivated during debugging.

By ensuring that these caches are cleared or disabled, you can eliminate caching as a variable when troubleshooting and ensure you are viewing the most recent, un-cached version of your WooCommerce site.

Always remember to re-enable these caching mechanisms once you’re done troubleshooting to ensure your site operates efficiently.