Hi @am0k,
Thank you for bringing this to our attention!
This error usually has to do with faulty API or conflicting plugin issues.
First, you could try to re-generate your API keys again:
Go to WooCommerce > Settings > API > Keys/Apps > Add Key > Permissions > Read/Write > Generate API key (don’t leave the description blank). Then copy both API Key and Secret in Printful > Settings > Stores > your Woocommerce store. Then go to Printful > Stores > View Store > Refresh data. The error should now be resolved.
Secondly, you could also try to disable any third-party plugins.
And lastly, try to switch to the default WooCommerce theme – Storefront. It could be a conflicting theme.
Let us know if the error still persists- our support team can be reached at [email protected]!