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SchemaUtil#replaceTypeReferences Issue When trying to re-built a GraphqlSchema #3384
Description
Describe the bug
graphql.schema.impl.SchemaUtil#replaceTypeReferences is breaking , when we are trying to re build the schema.
Issue occurring case :
When we traverse through a GraphqlObject node which has its interfaces resolved (replacedInterfaces!=null), those interfaces wont get registered into typeMap , as we are using
SchemaTraverser schemaTraverser = new SchemaTraverser(schemaElement -> schemaElement.getChildrenWithTypeReferences().getChildrenAsList());at later step when replaceTypeReferences tries to resolve graphqlobejcts interface types at method graphql.schema.GraphQLTypeResolvingVisitor#visitGraphQLObjectType of a resolved GraphqlObject node ( which have its resolved interfaces ) . it fails to resolve as there is not such interface registered in typeMap.
To Reproduce
one case where its necessary to rebuild an already built schema is while trying to create a readOnly Schema
GraphQLSchema.newSchema(schema).mutation((GraphQLObjectType) null).build()
Activity
Fix 5 open issues: subscription memory leak, cyclical directives, dup…
fix: handle already-resolved type references when rebuilding schema
andimarek commentedon May 20, 2026
Fixed by #4390.
The root cause was that schema rebuild type collection traverses the original type-reference child view via
getChildrenWithTypeReferences(), while already-built schema accessors can return resolved strong references such as implemented interfaces and union member types. After removing a root type, those resolved references could still be reachable through a remaining schema element but missing from the rebuilt type map, leading to the NPE inGraphQLTypeResolvingVisitor.#4390 extends
GraphQLTypeCollectingVisitorto collect those resolved object/interface/union relationships and adds regression coverage for direct schema rebuild andSchemaTransformer.transformSchemaWithDeletes(...). The PR merged with the required CI checks green.