A WooCommerce store using the WooCommerce Authorize.Net Gateway plugin ran into a checkout-blocking validation issue for an international customer. The customer selected Singapore as the billing country, but checkout still returned the error message: billing region is a required field.
Freshy traced the issue to the gateway plugin’s billing validation behavior, not Authorize.Net itself. The solution was a targeted compatibility patch that exempts countries without billing regions from the plugin’s forced billing state requirement, while preserving normal validation for countries that do use states or regions.
Issue Background
The store was running WooCommerce with the WooCommerce Authorize.Net Gateway plugin. A customer attempting to place an order with a Singapore billing address could not complete checkout because the site returned this validation error:
billing region is a required fieldThis was confusing because Singapore does not use a billing state/region field in the same way countries like the United States do. WooCommerce core normally accounts for countries that do not require a region field, but the gateway plugin was still expecting a value for billing_state.
The issue had extra complexity because similar orders had previously succeeded. That made it important to determine whether the failure was caused by a recent plugin update, a configuration change, cached customer data, or a longstanding plugin behavior that had only recently surfaced.
Diagnosis
Freshy reviewed the checkout behavior, recent site changes, and the payment flow. The issue was isolated to the WooCommerce Authorize.Net Gateway plugin. The payment processor itself was not the cause.
The plugin was forcing the billing region field to be required when the store’s base country was set to the United States. WooCommerce core recognized that Singapore does not require a region field, but the gateway plugin overrode that expected behavior and still required billing_state.
The investigation also found that this behavior was not caused by a recent update. The validation logic appeared to be a longstanding plugin behavior. Previous successful orders likely passed because a saved customer session or account value had prefilled the hidden billing state field with an older value. Once that saved value was no longer present, the hidden-but-required field was blank, causing checkout to fail.
Resolution Steps
The fix was to add a narrow compatibility patch for countries that do not use billing states or regions. The goal was not to disable billing validation globally. Instead, the patch needed to preserve the WooCommerce Authorize.Net Gateway plugin’s normal behavior while restoring WooCommerce’s expected handling for countries without regions.
A typical approach is to identify countries where WooCommerce does not require a billing state, then bypass or safely populate the gateway plugin’s required billing_state validation only for those countries.
if ( in_array( $billing_country, array( 'SG', 'AE' ), true ) ) {
// Exempt countries without billing regions from the gateway's billing_state requirement.
$requires_billing_state = false;
}For this case, the compatibility patch focused on countries such as Singapore and the UAE, where a state or region field may not be applicable. After the patch was deployed, Freshy tested the checkout flow to confirm that international customers from affected countries could complete checkout successfully.
The team also verified that the change did not interfere with standard checkout behavior for countries where a billing state remains required.
Final Outcome
The production patch resolved the WooCommerce checkout error. A subsequent Singapore order confirmed that the fix was working as intended.
The final result was a more reliable international checkout experience without weakening validation for other regions. The WooCommerce Authorize.Net Gateway plugin continued to function normally, while countries without billing regions were no longer blocked by the false billing region is a required field error.
If your WooCommerce checkout is failing for international customers because of a billing state, billing region, or Authorize.Net Gateway validation issue, contact Freshy for help diagnosing and fixing the problem.
