Error when accessing Store > Configuration > Sales > Payment Methods

[kartguru]

Error when accessing Store > Configuration > Sales > Payment Methods

[chnorton]

From memory this is something to do with the DI compilation not having been updated/re-run, so Magento passes through a generic ObjectManager rather than an instance with the interface you expect. I'll take a look at it and see if I can get you more specific information about how to solve it.

[chnorton]

OK, so the issue is with the fontis/customergroupaccess-mage2 library not being a "proper" Magento 2 library so it wasn't working with the DI system as you'd expect. This was fine in dev mode, but production mode doesn't compile it properly and causes the error you're seeing. The customergroupaccess-mage2 library has been updated to version 1.0.1 now, so updating to that version should resolve this.

Hopefully it's a simple composer update fontis/customergroupaccess-mage2 away!