node.js – Variable of required type was not provided at graphql

I’m trying to send a query with qraphql. I’m trying to get userId as variable from arguments at resolver, but I have en error “Variable “$userId” of required type “UUID!” was not provided.”

const Query = new GraphQLObjectType({
  name: 'Query',
  fields: {
    user: {
      type: userType,
      description: 'Get user by Id',
      args: {
        id: {
          type: UUIDType,
        },
      },
      resolve: async (_, args: { userId: string }, _context) => {
        try {
        const user = await prisma.user.findUnique({
          where: {
            id: args.userId,
          },
        });
        return user;
      } catch {
        return null;
      }
      },
    }
})

userType is:

export const userType = new GraphQLObjectType({
  name: 'User',
  fields: () => ({
    id: { type: new GraphQLNonNull(UUIDType) },
    name: { type: new GraphQLNonNull(GraphQLString) },
    balance: { type: new GraphQLNonNull(GraphQLFloat) },
  })
});

The query is:

query ($userId: UUID!) {
        user(id: $userId) {
            id
            name
            balance
        }
    }

Why do I have this error?

I tried to find any information, but useless