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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"NonNullableValueCoercedAsNullException being thrown in QueryTraversal","articleBody":"\r\n\r\n\r\n### Discussed in https://github.com/graphql-java/graphql-java/discussions/2760\r\n\r\n\u003cdiv type='discussions-op-text'\u003e\r\n\r\n\u003csup\u003eOriginally posted by **slisaasquatch** March 12, 2022\u003c/sup\u003e\r\nI'm seeing random `NonNullableValueCoercedAsNullException`s from our servers running graphql-java 17.3 with graphql-java-tools 12.0.2. I've logged the entire GraphQL query, variables, and operation name, and I cannot reproduce the exception. The stack trace looks like this:\r\n\r\n```\r\ngraphql.execution.NonNullableValueCoercedAsNullException: Field '' has coerced Null value for NonNull type 'String!'\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValue(ValuesResolver.java:493)\r\n\tat graphql.execution.ValuesResolver.lambda$externalValueToInternalValueForList$2(ValuesResolver.java:604)\r\n\tat java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)\r\n\tat java.util.ArrayList$ArrayListSpliterator.forEachRemaining(ArrayList.java:1384)\r\n\tat java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:482)\r\n\tat java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:472)\r\n\tat java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)\r\n\tat java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)\r\n\tat java.util.stream.ReferencePipeline.collect(ReferencePipeline.java:566)\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValueForList(ValuesResolver.java:605)\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValue(ValuesResolver.java:507)\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValueForObject(ValuesResolver.java:570)\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValue(ValuesResolver.java:510)\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValue(ValuesResolver.java:491)\r\n\tat graphql.execution.ValuesResolver.externalValueToInternalValueForVariables(ValuesResolver.java:412)\r\n\tat graphql.execution.ValuesResolver.coerceVariableValues(ValuesResolver.java:94)\r\n\tat graphql.analysis.QueryTraverser.coerceVariables(QueryTraverser.java:64)\r\n\tat graphql.analysis.QueryTraverser.\u003cinit\u003e(QueryTraverser.java:60)\r\n\tat graphql.analysis.QueryTraverser.\u003cinit\u003e(QueryTraverser.java:40)\r\n\tat graphql.analysis.QueryTraverser$Builder.build(QueryTraverser.java:297)\r\n\tat graphql.analysis.MaxQueryDepthInstrumentation.newQueryTraverser(MaxQueryDepthInstrumentation.java:92)\r\n\tat graphql.analysis.MaxQueryDepthInstrumentation.lambda$beginValidation$2(MaxQueryDepthInstrumentation.java:57)\r\n\tat graphql.execution.instrumentation.SimpleInstrumentationContext.onCompleted(SimpleInstrumentationContext.java:51)\r\n\tat graphql.execution.instrumentation.ChainedInstrumentation$ChainedInstrumentationContext.lambda$onCompleted$1(ChainedInstrumentation.java:238)\r\n\tat graphql.com.google.common.collect.ImmutableList.forEach(ImmutableList.java:405)\r\n\tat graphql.execution.instrumentation.ChainedInstrumentation$ChainedInstrumentationContext.onCompleted(ChainedInstrumentation.java:238)\r\n\tat graphql.GraphQL.validate(GraphQL.java:600)\r\n\tat graphql.GraphQL.parseAndValidate(GraphQL.java:562)\r\n\tat graphql.GraphQL.lambda$parseValidateAndExecute$10(GraphQL.java:531)\r\n\tat graphql.execution.preparsed.NoOpPreparsedDocumentProvider.getDocument(NoOpPreparsedDocumentProvider.java:15)\r\n\tat graphql.GraphQL.parseValidateAndExecute(GraphQL.java:533)\r\n\tat graphql.GraphQL.executeAsync(GraphQL.java:502)\r\n```\r\n\r\nCan someone please give me some general directions on what the error means?\r\n\r\nI know if I put a `null` inside an array that requires non null values in `variables`, I can cause an error with the same error message. However, if you look at the stack trace, the exception was thrown at `graphql.GraphQL.executeAsync`, meaning I'm not even getting a result from it.\r\n\r\nAlso for the record, this is what my `variables` looks like:\r\n\r\n```json\r\n{\r\n  \"accountId\": \"133...63\",\r\n  \"userId\": \"133...63\",\r\n  \"userInput\": {\r\n    \"accountId\": \"133...63\",\r\n    \"id\": \"133...63\"\r\n  }\r\n}\r\n```\r\n\r\nI do not have arrays or nulls in my `variables`.\u003c/div\u003e","author":{"url":"https://github.com/bbakerman","@type":"Person","name":"bbakerman"},"datePublished":"2022-03-13T01:37:09.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":11},"url":"https://github.com/2761/graphql-java/issues/2761"}