Error: Only one resolver is allowed per field

The following GraphQL-Schema leads to the Error “Only one resolver is allowed per field” when pushed to the AWS Cloud.

type TypeA @model {
	id: ID!
	typeB: [TypeB!]! @connection(name: "myCon")
}
type TypeB @model {
	id: ID!
	typeA: TypeA! @connection(name: "myCon")
}

The generated Resolver and CloudFormation looks good to me. The Resolvers seems to be unique per Type and Field.

We had to rename the non-collection property to something else so the resolver could be deployed:

type TypeA @model {
	id: ID!
	typeB: [TypeB!]! @connection(name: "myCon")
}
type TypeB @model {
	id: ID!
	typeBTypeA: TypeA! @connection(name: "myCon")
}

I don’t know if this is a CloudFormation or a Amplify CLI Bug. There is a Forum Post (https://forums.aws.amazon.com/thread.jspa?messageID=884492&#884492) which I replied to because this can be that CloudFormation Bug. But since I use the Amplify CLI, I wanted to bring this up, even if it’s just for documentation.

[mikeparisstuff]

It seems there is some path that leaves APIs in a state where a resolver is left dangling even after the field is removed from the schema. When this happens you can get around the issue by going to the AppSync console, adding a field to the schema with the same name as the supposed conflict, delete the resolver record by selecting it from the right half of the schema page and clicking “Delete Resolver” on the resolver page.

I will try to reproduce and identify the underlying issue but it appears that it is not within the Amplify CLI itself.

[yonatanganot]

I found a solution for this error without losing the data.

Do the following actions for the affected types:

1. Add generated operations with null value inside @model: type Name @model(queries: null, mutations: null, subscriptions: null) {...}
2. amplify push
3. Remove generated operations with null value inside @model: type Name @model {...}
4. amplify push

Good luck!