WooCommerce: Error Your Authentication credentials have expired or are invalid

​​​​​​Hi @pmaly, 

Thanks for joining our Community and I’m sorry you’re experiencing this issue. @David To gave some helpful steps to follow on this thread:

Please try the following:

1. Completely remove (not Disable) the Shopify integration in Klaviyo: https://www.klaviyo.com/integration/woocommerce
2. Log out of your Klaviyo account
3. Fully clear the browser cache and close out of the browser
4. Log back into your Klaviyo account via an incognito window
5. Re-add WooCommerce from the All Integrations tab: https://www.klaviyo.com/integrations

Let us know if other questions come up. Have a great day! 

~Chloe