Federation error codes

When Apollo Gateway attempts to compose the schemas provided by your subgraphs into a supergraph schema, it confirms that:

The subgraphs are valid
The resulting supergraph schema is valid
The gateway has all of the information it needs to execute operations against the resulting schema

If Apollo Gateway encounters an error, composition fails. This document lists subgraph validation and composition error codes, along with their root causes.

Errors

The following errors might be raised during composition:

Code	Description	Since	Comment
`DEFAULT_VALUE_USES_INACCESSIBLE`	An element is marked as @inaccessible but is used in the default value of an element visible in the API schema.	2.0.0
`DIRECTIVE_COMPOSITION_ERROR`	Error when composing custom directives.	2.1.0
`DIRECTIVE_DEFINITION_INVALID`	A built-in or federation directive has an invalid definition in the schema.	2.0.0	Replaces: `TAG_DEFINITION_INVALID`
`DISALLOWED_INACCESSIBLE`	An element is marked as @inaccessible that is not allowed to be @inaccessible.	2.0.0
`DOWNSTREAM_SERVICE_ERROR`	Indicates an error in a subgraph service query during query execution in a federated service.	0.x
`EMPTY_MERGED_ENUM_TYPE`	An enum type has no value common to all the subgraphs that define the type. Merging that type would result in an invalid empty enum type.	2.0.0
`EMPTY_MERGED_INPUT_TYPE`	An input object type has no field common to all the subgraphs that define the type. Merging that type would result in an invalid empty input object type.	2.0.0
`ENUM_VALUE_MISMATCH`	An enum type that is used as both an input and output type has a value that is not defined in all the subgraphs that define the enum type.	2.0.0
`EXTENSION_WITH_NO_BASE`	A subgraph is attempting to `extend` a type that is not originally defined in any known subgraph.	0.x
`EXTERNAL_ARGUMENT_DEFAULT_MISMATCH`	An `@external` field declares an argument with a default that is incompatible with the corresponding argument in the declaration(s) of that field in other subgraphs.	2.0.0
`EXTERNAL_ARGUMENT_MISSING`	An `@external` field is missing some arguments present in the declaration(s) of that field in other subgraphs.	2.0.0
`EXTERNAL_ARGUMENT_TYPE_MISMATCH`	An `@external` field declares an argument with a type that is incompatible with the corresponding argument in the declaration(s) of that field in other subgraphs.	2.0.0
`EXTERNAL_COLLISION_WITH_ANOTHER_DIRECTIVE`	The @external directive collides with other directives in some situations.	2.1.0
`EXTERNAL_MISSING_ON_BASE`	A field is marked as `@external` in a subgraph but with no non-external declaration in any other subgraph.	0.x
`EXTERNAL_ON_INTERFACE`	The field of an interface type is marked with `@external`: as external is about marking field not resolved by the subgraph and as interface field are not resolved (only implementations of those fields are), an "external" interface field is nonsensical	2.0.0
`EXTERNAL_TYPE_MISMATCH`	An `@external` field has a type that is incompatible with the declaration(s) of that field in other subgraphs.	0.x
`EXTERNAL_UNUSED`	An `@external` field is not being used by any instance of `@key`, `@requires`, `@provides` or to satisfy an interface implementation.	0.x
`FIELD_ARGUMENT_DEFAULT_MISMATCH`	An argument (of a field/directive) has a default value that is incompatible with that of other declarations of that same argument in other subgraphs.	2.0.0
`FIELD_ARGUMENT_TYPE_MISMATCH`	An argument (of a field/directive) has a type that is incompatible with that of other declarations of that same argument in other subgraphs.	2.0.0	Replaces: `VALUE_TYPE_INPUT_VALUE_MISMATCH`
`FIELD_TYPE_MISMATCH`	A field has a type that is incompatible with other declarations of that field in other subgraphs.	2.0.0	Replaces: `VALUE_TYPE_FIELD_TYPE_MISMATCH`
`IMPLEMENTED_BY_INACCESSIBLE`	An element is marked as @inaccessible but implements an element visible in the API schema.	2.0.0
`INPUT_FIELD_DEFAULT_MISMATCH`	An input field has a default value that is incompatible with other declarations of that field in other subgraphs.	2.0.0
`INTERFACE_FIELD_NO_IMPLEM`	After subgraph merging, an implementation is missing a field of one of the interface it implements (which can happen for valid subgraphs).	2.0.0
`INTERFACE_KEY_MISSING_IMPLEMENTATION_TYPE`	A subgraph has a `@key` on an interface type, but that subgraph does not define an implementation (in the supergraph) of that interface	2.3.0
`INTERFACE_KEY_NOT_ON_IMPLEMENTATION`	A `@key` is defined on an interface type, but is not defined (or is not resolvable) on at least one of the interface implementations	2.3.0
`INTERFACE_OBJECT_USAGE_ERROR`	Error in the usage of the @interfaceObject directive.	2.3.0
`INVALID_FEDERATION_SUPERGRAPH`	Indicates that a schema provided for an Apollo Federation supergraph is not a valid supergraph schema.	2.1.0
`INVALID_FIELD_SHARING`	A field that is non-shareable in at least one subgraph is resolved by multiple subgraphs.	2.0.0
`INVALID_GRAPHQL`	A schema is invalid GraphQL: it violates one of the rule of the specification.	2.0.0
`INVALID_LINK_DIRECTIVE_USAGE`	An application of the @link directive is invalid/does not respect the specification.	2.0.0
`INVALID_LINK_IDENTIFIER`	A url/version for a @link feature is invalid/does not respect the specification.	2.1.0
`INVALID_SHAREABLE_USAGE`	The `@shareable` federation directive is used in an invalid way.	2.1.2
`INVALID_SUBGRAPH_NAME`	A subgraph name is invalid (subgraph names cannot be a single underscore ("_")).	2.0.0
`KEY_DIRECTIVE_IN_FIELDS_ARG`	The `fields` argument of a `@key` directive includes some directive applications. This is not supported	2.1.0
`KEY_FIELDS_HAS_ARGS`	The `fields` argument of a `@key` directive includes a field defined with arguments (which is not currently supported).	2.0.0
`KEY_FIELDS_SELECT_INVALID_TYPE`	The `fields` argument of `@key` directive includes a field whose type is a list, interface, or union type. Fields of these types cannot be part of a `@key`	0.x
`KEY_INVALID_FIELDS_TYPE`	The value passed to the `fields` argument of a `@key` directive is not a string.	2.0.0
`KEY_INVALID_FIELDS`	The `fields` argument of a `@key` directive is invalid (it has invalid syntax, includes unknown fields, ...).	2.0.0
`KEY_UNSUPPORTED_ON_INTERFACE`	A `@key` directive is used on an interface, which is only supported when @linking to federation 2.3+.	2.0.0
`LINK_IMPORT_NAME_MISMATCH`	The import name for a merged directive (as declared by the relevant `@link(import:)` argument) is inconsistent between subgraphs.	2.0.0
`MERGED_DIRECTIVE_APPLICATION_ON_EXTERNAL`	In a subgraph, a field is both marked @external and has a merged directive applied to it	2.0.0
`NO_QUERIES`	None of the composed subgraphs expose any query.	2.0.0
`ONLY_INACCESSIBLE_CHILDREN`	A type visible in the API schema has only @inaccessible children.	2.0.0
`OVERRIDE_COLLISION_WITH_ANOTHER_DIRECTIVE`	The @override directive cannot be used on external fields, nor to override fields with either @external, @provides, or @requires.	2.0.0
`OVERRIDE_FROM_SELF_ERROR`	Field with `@override` directive has "from" location that references its own subgraph.	2.0.0
`OVERRIDE_LABEL_INVALID`	The @override directive `label` argument must match the pattern /¹[a-zA-Z0-9_-:./]*$/ or /^percent((d{1,2}(.d{1,8})?	100))$/	2.7.0
`OVERRIDE_ON_INTERFACE`	The @override directive cannot be used on the fields of an interface type.	2.3.0
`OVERRIDE_SOURCE_HAS_OVERRIDE`	Field which is overridden to another subgraph is also marked @override.	2.0.0
`PROVIDES_DIRECTIVE_IN_FIELDS_ARG`	The `fields` argument of a `@provides` directive includes some directive applications. This is not supported	2.1.0
`PROVIDES_FIELDS_HAS_ARGS`	The `fields` argument of a `@provides` directive includes a field defined with arguments (which is not currently supported).	2.0.0
`PROVIDES_FIELDS_MISSING_EXTERNAL`	The `fields` argument of a `@provides` directive includes a field that is not marked as `@external`.	0.x
`PROVIDES_INVALID_FIELDS_TYPE`	The value passed to the `fields` argument of a `@provides` directive is not a string.	2.0.0
`PROVIDES_INVALID_FIELDS`	The `fields` argument of a `@provides` directive is invalid (it has invalid syntax, includes unknown fields, ...).	2.0.0
`PROVIDES_ON_NON_OBJECT_FIELD`	A `@provides` directive is used to mark a field whose base type is not an object type.	2.0.0
`PROVIDES_UNSUPPORTED_ON_INTERFACE`	A `@provides` directive is used on an interface, which is not (yet) supported.	2.0.0
`QUERY_ROOT_TYPE_INACCESSIBLE`	An element is marked as @inaccessible but is the query root type, which must be visible in the API schema.	2.0.0
`REFERENCED_INACCESSIBLE`	An element is marked as @inaccessible but is referenced by an element visible in the API schema.	2.0.0
`REQUIRED_ARGUMENT_MISSING_IN_SOME_SUBGRAPH`	An argument of a field or directive definition is mandatory in some subgraphs, but the argument is not defined in all the subgraphs that define the field or directive definition.	2.0.0
`REQUIRED_INACCESSIBLE`	An element is marked as @inaccessible but is required by an element visible in the API schema.	2.0.0
`REQUIRED_INPUT_FIELD_MISSING_IN_SOME_SUBGRAPH`	A field of an input object type is mandatory in some subgraphs, but the field is not defined in all the subgraphs that define the input object type.	2.0.0
`REQUIRES_DIRECTIVE_IN_FIELDS_ARG`	The `fields` argument of a `@requires` directive includes some directive applications. This is not supported	2.1.0
`REQUIRES_FIELDS_MISSING_EXTERNAL`	The `fields` argument of a `@requires` directive includes a field that is not marked as `@external`.	0.x
`REQUIRES_INVALID_FIELDS_TYPE`	The value passed to the `fields` argument of a `@requires` directive is not a string.	2.0.0
`REQUIRES_INVALID_FIELDS`	The `fields` argument of a `@requires` directive is invalid (it has invalid syntax, includes unknown fields, ...).	2.0.0
`REQUIRES_UNSUPPORTED_ON_INTERFACE`	A `@requires` directive is used on an interface, which is not (yet) supported.	2.0.0
`ROOT_MUTATION_USED`	A subgraph's schema defines a type with the name `mutation`, while also specifying a different type name as the root query object. This is not allowed.	0.x
`ROOT_QUERY_USED`	A subgraph's schema defines a type with the name `query`, while also specifying a different type name as the root query object. This is not allowed.	0.x
`ROOT_SUBSCRIPTION_USED`	A subgraph's schema defines a type with the name `subscription`, while also specifying a different type name as the root query object. This is not allowed.	0.x
`SATISFIABILITY_ERROR`	Subgraphs can be merged, but the resulting supergraph API would have queries that cannot be satisfied by those subgraphs.	2.0.0
`SHAREABLE_HAS_MISMATCHED_RUNTIME_TYPES`	A shareable field return type has mismatched possible runtime types in the subgraphs in which the field is declared. As shared fields must resolve the same way in all subgraphs, this is almost surely a mistake.	2.0.0
`SOURCE_API_HTTP_BASE_URL_INVALID`	The `@sourceAPI` directive must specify a valid http.baseURL	2.7.0
`SOURCE_API_NAME_INVALID`	Each `@sourceAPI` directive must take a unique and valid name as an argument	2.7.0
`SOURCE_API_PROTOCOL_INVALID`	Each `@sourceAPI` directive must specify exactly one of the known protocols	2.7.0
`SOURCE_FEDERATION_VERSION_REQUIRED`	Schemas using `@source{API,Type,Field}` directives must @link-import v2.7 or later of federation	2.7.1
`SOURCE_FIELD_API_ERROR`	The `api` argument of the `@sourceField` directive must match a valid `@sourceAPI` name	2.7.0
`SOURCE_FIELD_HTTP_BODY_INVALID`	If `@sourceField` specifies http.body, it must be a valid `JSONSelection` matching available arguments and fields	2.7.0
`SOURCE_FIELD_HTTP_METHOD_INVALID`	The `@sourceField` directive must specify at most one of `http.{GET,POST,PUT,PATCH,DELETE}`	2.7.0
`SOURCE_FIELD_HTTP_PATH_INVALID`	The `@sourceField` directive must specify a valid URL template for `http.{GET,POST,PUT,PATCH,DELETE}`	2.7.0
`SOURCE_FIELD_NOT_ON_ROOT_OR_ENTITY_FIELD`	The `@sourceField` directive must be applied to a field of the `Query` or `Mutation` types, or of an entity type	2.7.0
`SOURCE_FIELD_PROTOCOL_INVALID`	If `@sourceField` specifies a protocol, it must match the corresponding `@sourceAPI` protocol	2.7.0
`SOURCE_FIELD_SELECTION_INVALID`	The `selection` argument of the `@sourceField` directive must be a valid `JSONSelection` that outputs fields of the GraphQL type	2.7.0
`SOURCE_HTTP_HEADERS_INVALID`	The `http.headers` argument of `@source*` directives must specify valid HTTP headers	2.7.0
`SOURCE_TYPE_API_ERROR`	The `api` argument of the `@sourceType` directive must match a valid `@sourceAPI` name	2.7.0
`SOURCE_TYPE_HTTP_BODY_INVALID`	If the `@sourceType` specifies `http.body`, it must be a valid `JSONSelection`	2.7.0
`SOURCE_TYPE_HTTP_METHOD_INVALID`	The `@sourceType` directive must specify exactly one of `http.GET` or `http.POST`	2.7.0
`SOURCE_TYPE_HTTP_PATH_INVALID`	The `@sourceType` directive must specify a valid URL template for `http.GET` or `http.POST`	2.7.0
`SOURCE_TYPE_ON_NON_OBJECT_OR_NON_ENTITY`	The `@sourceType` directive must be applied to an object or interface type that also has `@key`	2.7.0
`SOURCE_TYPE_PROTOCOL_INVALID`	The `@sourceType` directive must specify the same protocol as its corresponding `@sourceAPI`	2.7.0
`SOURCE_TYPE_SELECTION_INVALID`	The `selection` argument of the `@sourceType` directive must be a valid `JSONSelection` that outputs fields of the GraphQL type	2.0.0
`TYPE_DEFINITION_INVALID`	A built-in or federation type has an invalid definition in the schema.	2.0.0
`TYPE_KIND_MISMATCH`	A type has the same name in different subgraphs, but a different kind. For instance, one definition is an object type but another is an interface.	2.0.0	Replaces: `VALUE_TYPE_KIND_MISMATCH`, `EXTENSION_OF_WRONG_KIND`, `ENUM_MISMATCH_TYPE`
`TYPE_WITH_ONLY_UNUSED_EXTERNAL`	A federation 1 schema has a composite type comprised only of unused external fields. Note that this error can only be raised for federation 1 schema as federation 2 schema do not allow unused external fields (and errors with code EXTERNAL_UNUSED will be raised in that case). But when federation 1 schema are automatically migrated to federation 2 ones, unused external fields are automatically removed, and in rare case this can leave a type empty. If that happens, an error with this code will be raised	2.0.0
`UNKNOWN_FEDERATION_LINK_VERSION`	The version of federation in a @link directive on the schema is unknown.	2.0.0
`UNKNOWN_LINK_VERSION`	The version of @link set on the schema is unknown.	2.1.0
`UNSUPPORTED_FEATURE`	Indicates an error due to feature currently unsupported by federation.	2.1.0
`UNSUPPORTED_LINKED_FEATURE`	Indicates that a feature used in a @link is either unsupported or is used with unsupported options.	2.0.0

Removed codes

The following error codes have been removed and are no longer generated by the most recent version of the @apollo/gateway library:

Removed Code	Comment
`DUPLICATE_ENUM_DEFINITION`	As duplicate enum definitions is invalid GraphQL, this will now be an error with code `INVALID_GRAPHQL`.
`DUPLICATE_ENUM_VALUE`	As duplicate enum values is invalid GraphQL, this will now be an error with code `INVALID_GRAPHQL`.
`DUPLICATE_SCALAR_DEFINITION`	As duplicate scalar definitions is invalid GraphQL, this will now be an error with code `INVALID_GRAPHQL`.
`ENUM_MISMATCH`	Subgraph definitions for an enum are now merged by composition.
`EXTERNAL_USED_ON_BASE`	As there is not type ownership anymore, there is also no particular limitation as to where a field can be external.
`INTERFACE_FIELD_IMPLEM_TYPE_MISMATCH`	This error was thrown by a validation introduced to avoid running into a known runtime bug. Since federation 2.3, the underlying runtime bug has been addressed and the validation/limitation was no longer necessary and has been removed.
`KEY_FIELDS_MISSING_EXTERNAL`	Using `@external` for key fields is now discouraged, unless the field is truly meant to be external.
`KEY_FIELDS_MISSING_ON_BASE`	Keys can now use any field from any other subgraph.
`KEY_MISSING_ON_BASE`	Each subgraph is now free to declare a key only if it needs it.
`KEY_NOT_SPECIFIED`	Each subgraph can declare key independently of any other subgraph.
`MULTIPLE_KEYS_ON_EXTENSION`	Every subgraph can have multiple keys, as necessary.
`NON_REPEATABLE_DIRECTIVE_ARGUMENTS_MISMATCH`	Since federation 2.1.0, the case this error used to cover is now a warning (with code `INCONSISTENT_NON_REPEATABLE_DIRECTIVE_ARGUMENTS`) instead of an error.
`PROVIDES_FIELDS_SELECT_INVALID_TYPE`	@provides can now be used on field of interface, union and list types.
`PROVIDES_NOT_ON_ENTITY`	@provides can now be used on any type.
`REQUIRES_FIELDS_HAS_ARGS`	Since federation 2.1.1, using fields with arguments in a @requires is fully supported.
`REQUIRES_FIELDS_MISSING_ON_BASE`	Fields in @requires can now be from any subgraph.
`REQUIRES_USED_ON_BASE`	As there is not type ownership anymore, there is also no particular limitation as to which subgraph can use a @requires.
`RESERVED_FIELD_USED`	This error was previously not correctly enforced: the _service and _entities, if present, were overridden; this is still the case.
`VALUE_TYPE_NO_ENTITY`	There is no strong different between entity and value types in the model (they are just usage pattern) and a type can have keys in one subgraph but not another.
`VALUE_TYPE_UNION_TYPES_MISMATCH`	Subgraph definitions for an union are now merged by composition.

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Query plans

Composition hints