graphql Errors
20 error patterns
GraphQL field not found on type
Cannot query field.*on type
- •Check the schema — the field may be named differently or not exist on that type
- •Run introspection query to verify available fields
GraphQL variable type mismatch
Expected type.*found.*type mismatch|Variable.*got invalid value
- •Ensure variable types match the schema definition (e.g., ID! vs String!)
- •Check that enum values are passed as unquoted strings, not quoted
GraphQL N+1 query problem
N\+1.*detected|dataloader.*batch|too many queries
- •Use DataLoader to batch and cache database calls per request
- •Implement field-level resolvers with DataLoader instances
Resolver returned null for non-nullable field
resolver.*returned undefined|Cannot return null for non-nullable field
- •Ensure resolver returns a value or change schema to nullable (remove !)
- •Add error handling in resolver to throw GraphQLError instead of returning null
GraphQL authentication/authorization error
Context.*authenticated|Not authorized|UNAUTHENTICATED
- •Pass auth token in context via the server middleware/plugin setup
- •Verify the context function extracts and validates the JWT/session
GraphQL subscription WebSocket connection failure
subscription.*connection.*closed|WebSocket.*failed|SUBSCRIPTION_FAIL
- •Verify WebSocket server is configured (ws:// or wss:// protocol)
- •Check that connectionParams passes auth token for subscriptions
GraphQL schema missing Query type
Schema must contain.*Query type|type Query.*not found
- •Define at minimum a Query type in your schema: type Query { ... }
- •Check that schema merging/stitching includes the base Query type
Duplicate type definition in schema
Duplicate type.*definition|Type.*already defined
- •Use extend type Query { } in modular schemas instead of redefining Query
- •Check for duplicate type names across schema files
GraphQL fragment type condition error
Validation error.*fragment.*on.*type|fragment.*cannot be spread
- •Ensure fragment is defined on the correct type or interface
- •Use inline fragments with ... on TypeName for union type selections
GraphQL query depth/complexity limit exceeded
Maximum.*depth.*exceeded|query.*too complex|complexity limit
- •Simplify nested queries or split into multiple queries
- •Increase depth limit if legitimate use case (configure in validation rules)
GraphQL mutation input validation error
Mutation.*input.*invalid|Input type.*not provided
- •Check that all required fields in the input type are provided
- •Verify the input object structure matches the schema's input type definition
Invalid enum value in GraphQL query
enum.*not.*valid|Expected.*enum.*received
- •Pass enum values without quotes: status: ACTIVE not status: 'ACTIVE'
- •Check available enum values in schema definition
Automatic Persisted Query cache miss
Persisted query not found|APQ.*hash.*mismatch
- •Client should retry with full query body when server returns 'not found'
- •Ensure APQ cache (Redis/in-memory) is shared across server instances
GraphQL union/interface missing resolveType
Union.*type.*must.*resolve|__resolveType.*missing|Abstract type.*resolve
- •Add __resolveType function to union/interface resolver map
- •Return __typename field from the resolver for automatic type resolution
GraphQL file upload configuration error
Upload.*scalar.*not configured|multipart.*request.*failed
- •Install and configure graphql-upload package for multipart request handling
- •Add Upload scalar to schema and configure the server middleware
GraphQL query batching failure
Batching.*timeout|batch.*request.*failed
- •Increase batch timeout configuration on the client link
- •Check server supports batched queries (array of operations)
Apollo Client cache normalization error
Cache.*inconsistenc|normalizedCache.*missing.*id|cache.*evict.*error
- •Ensure all types return an id or _id field for cache normalization
- •Configure typePolicies with keyFields for types without standard id
Unknown GraphQL directive
Directive.*not found|Unknown directive.*@
- •Define custom directives in schema and implement transformer/visitor
- •Check directive name spelling and that it's registered with the schema
Apollo Federation subgraph resolution error
Federation.*subgraph.*error|_entities.*resolver.*failed
- •Ensure __resolveReference is implemented for federated entity types
- •Check that @key directive fields are queryable in the subgraph
GraphQL rate limiting triggered
Rate limit.*exceeded|throttle.*graphql|too many requests
- •Implement query cost analysis to assign weights to fields
- •Add per-client rate limiting based on token/IP in context