graphql POST request returns 404 not found [closed]

graphql POST request returns 404 not found [closed]

I am testing a graphql endpoint that uses POST requests with persisted queries, I tried the following query:

{
"query":"query{signedUser}"
}

The graphql endpoint returns an error that signedUser doesn't exist on the query and suggest signedInUser. When I change it, the endpoint returns error 404 not found.