Fixing WooCommerce checkout failures and “Unknown error while connecting to PayPal” caused by deprecated PayPal Standard conflicts
When customers began reporting failed orders and frozen checkout pages on a WooCommerce site, Freshy’s development team was brought in to investigate. The issue was costing sales and frustrating users attempting to complete purchases. After a deep dive, Freshy identified a conflict between outdated and new PayPal gateways that was preventing checkout from processing correctly.
Issue background
The client reported two major problems affecting checkout:
- The Apartment/Building field was incorrectly set as required, blocking business customers from proceeding.
- Even after bypassing that field, the checkout page would freeze after submission, never completing the order or redirecting to confirmation.
This behavior was particularly disruptive, as it caused customers’ browsers to hang indefinitely and required manual order processing by phone—creating a poor user experience and loss of revenue.
Diagnosis
After confirming that the address field requirement had already been resolved, Freshy focused on the checkout submission failure. Developer testing revealed:
- The issue occurred with PayPal Payments integration on both guest and logged-in sessions.
- Console logs displayed a JavaScript error:
Unknown error while connecting to PayPal. Status code: 0. - This suggested a communication failure between the WooCommerce checkout process and PayPal’s API endpoint.
A closer inspection of the site’s active payment methods revealed the likely cause:
- PayPal Standard (deprecated)
- PayPal Payments
- Advanced Card Processing (part of the PayPal Payments module)
The older “PayPal Standard” gateway was still active, conflicting with the newer PayPal Payments integration. As both attempted to initialize simultaneously, API calls were being blocked or duplicated—resulting in stalled submissions and incomplete checkouts.
Resolution steps
- Reproduced the issue in staging
Using a sandbox PayPal account, the Freshy team recreated the checkout failure on a staging site to safely isolate and test the issue. - Verified plugin versions
WooCommerce and PayPal Payments were found to be several updates behind. The outdated PayPal version lacked compatibility improvements for WooCommerce’s newer REST checkout endpoints. - Updated core plugins
Freshy updated both WooCommerce and PayPal Payments to their latest stable releases. After doing so, the PayPal API began responding correctly on the staging site. - Disabled deprecated gateway
PayPal Standard was fully deactivated, eliminating the possibility of conflicting API calls. The newer PayPal Payments plugin was configured to handle both PayPal and credit card transactions under one unified setup. - Confirmed checkout flow
Extensive testing confirmed that all checkout methods—PayPal, Advanced Card Processing, and standard credit card—processed successfully without timeouts or stalls. - Client approval and deployment
Once verified, updates were deployed to the live site. The client tested multiple checkout scenarios and confirmed successful order completion across all payment types.
Final outcome
After the fix:
- Checkout forms no longer froze or timed out after submission.
- PayPal integrations worked seamlessly across payment types.
- Business customers could complete orders without entering unnecessary address details.
- The site experienced a marked reduction in failed transaction reports.
Key takeaway
Running multiple PayPal integrations can create silent API conflicts that block checkout without visible errors. Freshy’s quick diagnosis and cleanup restored checkout reliability and safeguarded ongoing sales.
For WooCommerce stores, regularly auditing active payment gateways and plugin versions is critical to maintaining transaction stability—especially when multiple gateways serve similar roles.
Having trouble with WooCommerce checkout or payment gateway conflicts?
Contact Freshy today to ensure your checkout process runs smoothly and your payment integrations stay up to date.
