Hello Robin,
I’ve checked the the WooCommerce filter implementation, it expects an array
as a parameter. I suspect there must be incorrect implementation for woocommerce_available_payment_gateways
filter somewhere in your codebase (other plugins, theme, custom code) Filter should always return array
but it’s returning nothing. Filters are applied in the order. Our filter runs after the faulty one and instead of getting proper type array
it’s getting null
value.
You should search for the woocommerce_available_payment_gateways
in you codebase and look for the method that have no return statement ot returns null.
If needed I can assist in pinpointing where is the incorrect filter implementation placed. For this I would need access to your codebase where I can search for the filter use.