<?php namespace ProcessWire;

$ProcessGraphQL = $modules->get('ProcessGraphQL');
$ProcessGraphQL->GraphQLServerUrl = $config->urls->root . '/graphql/';
echo $ProcessGraphQL->executeGraphiQL();

<?php namespace ProcessWire;

$ProcessGraphQL = $modules->get('ProcessGraphQL');
$ProcessGraphQL->GraphQLServerUrl = '/graphql/';
echo $ProcessGraphQL->executeGraphiQL();

Fix the graphql server url.
Fix the graphql server url.
