Table of Contents
Problem Description #
After a period of normal operation, UK VAT number validation suddenly fails. On checkout (or VAT input), users see the message: “Validation failed. Please try again.” This affects UK customers and prevents proper VAT exemption or validation.
Common symptoms
- “Validation failed. Please try again.” message at checkout. WordPress.org
- Previously valid UK VAT numbers are now rejected.
- The issue affects many users, not isolated to one site or number.
Cause
- The external API/service used for UK VAT verification was changed by the UK tax authorities (or VAT lookup service), the plugin’s original validation method became outdated. In one reported case, the plugin maintainers confirmed the issue and released a fix: switching UK VAT validation to use a new service (VATSense) instead of the older API. WordPress.org
- Sites that haven’t updated to the patched plugin version (after the service change) remain broken.
Solution (step‑by‑step)
- Update plugin to the latest version. The fix was released in version 4.3.2 (or newer) which switches to the updated validation service. WordPress.org+1
- Obtain and configure the new API key (if required): For VATSense (or whichever service the plugin uses), fetch the free API key (free up to certain checks/month) and enter it in WP Admin → WPFactory → EU VAT → Validation tab. WordPress.org
- Clear caches and test again: Clear any server, CDN or caching plugin cache. Then open checkout as new user and test a known valid UK VAT number.
- If validation still fails: Verify the VAT number format (include country code prefix, e.g. “GB0123456789”) and ensure there are no spaces or invalid characters. If still failing, contact plugin support with the VAT number (you can mask part of it), site URL, WP/WC versions, and theme info.
Prerequisites
- Plugin updated to version 4.3.2 or later.
- Valid VATSense (or configured) API key if required.
- WordPress and WooCommerce updated.
Additional Notes
- The issue was caused by external API changes, future external changes may also break validation again. Check plugin changelog and support announcements after each plugin update.
- Make sure to test validation periodically (esp. after plugin/theme updates) to catch silently broken VAT checks.
