Debugging WooCommerce Subscriptions

Guest users on a fitness membership site were seeing full prices instead of the advertised 7-day free trial, while logged-in users saw everything perfectly. This is a classic "logged-in vs. guest" discrepancy that usually points to caching, but in this case, it was a deeper logic failure in the conversion funnel.

The "Caching" Red Herring

When a site behaves differently for guests and logged-in users, the immediate instinct is to blame the cache. This site had a heavy stack: page cache, reverse proxy, and persistent object cache. Since guest requests are cached aggressively, it seemed obvious that guests were just seeing a stale version of the page.

I went down the rabbit hole of purging everything:

• Purged page cache: No effect.
• Purged reverse-proxy: No effect.
• Flushed object cache via WP-CLI: No effect.

To be 100% sure, I used cache-busting query strings and checked the response headers. The headers explicitly confirmed a MISS (freshly generated by PHP), yet the trial was still missing. This proved the issue was in the application logic, not the delivery layer.

The Process of Elimination

Since it wasn't the cache, I had to strip the stack down to find the leak. I spent a few days ruling out the usual suspects:

• Product Config: Checked variations. The 7-day trial was set correctly in the admin for all products.
• Custom Snippets: Ran a grep across theme files and must-use plugins for any logic tied to is_user_logged_in() or price overrides. Nothing.
• Dynamic Pricing: Tested with a standard "Customer" role account. The trial appeared. This meant it wasn't a specific User Role restriction, but a binary "Auth vs. Anon" issue.
• Subscription Enhancers: Traced the logic of a third-party trial-limiting plugin. It only triggered for logged-in users to prevent trial abuse, so it couldn't be the reason guests were blocked.

Deep Dive into the Core Logic

I started tracing the WooCommerce Subscriptions core execution path. I followed the data from the database to the frontend:
1. The function that retrieves the trial length from the product metadata.
2. The logic that converts that integer into the "7-day free trial" string.
3. The final HTML assembly for the price display.

Surprisingly, none of the core WooCommerce functions contained a login check. The data was flowing correctly through the system, but somehow, the final output for guests was being stripped of the trial value.

Practical Debugging Tip: The "Isolate and Conquer" Workflow

When you hit a wall like this where "everything looks correct" but the output is wrong, stop looking at the code and start looking at the environment. Here is the workflow I used to finally narrow this down:

1. Environment Sync: Ensure your local dev environment mirrors the production cache settings. If it doesn't happen locally, it's likely a server-level config.
2. Query Monitoring: Install Query Monitor to see exactly which filters are hooking into the price display.
3. The "Binary Search" Plugin Method:
- Disable all plugins except WooCommerce and WooCommerce Subscriptions.
- If the trial reappears for guests, enable plugins in batches of 5 until it breaks again.
- This is tedious but prevents you from missing a "silent" override in a plugin you thought was irrelevant.

For anyone managing a subscription site, always verify your checkout flow in an Incognito window. If you only test as an Admin or a Test Customer, you're missing the most critical part of your funnel: the first-time visitor.