{"record":{"id":"4bcbbf227cf24087","repo":"FasterXML/jackson-databind","slug":"cannot-use-formatschema-of-type-for-format","errorCode":null,"errorMessage":"Cannot use FormatSchema of type {} for format {}","messagePattern":"Cannot use FormatSchema of type (.+?) for format (.+?)","errorType":"exception","errorClass":"IllegalArgumentException","httpStatus":null,"severity":"error","filePath":"src/main/java/tools/jackson/databind/ObjectReader.java","lineNumber":2093,"sourceCode":"                if (_valueToUpdate != null) {\n                    bt = _valueToUpdate.getClass();\n                }\n            }\n            ctxt.reportTrailingTokens(bt, p, t);\n        }\n    }\n\n    /*\n    /**********************************************************************\n    /* Internal methods, other\n    /**********************************************************************\n     */\n\n    protected void _verifySchemaType(FormatSchema schema)\n    {\n        if (schema != null) {\n            if (!_parserFactory.canUseSchema(schema)) {\n                    throw new IllegalArgumentException(\"Cannot use FormatSchema of type \"+schema.getClass().getName()\n                            +\" for format \"+_parserFactory.getFormatName());\n            }\n        }\n    }\n\n    /**\n     * Internal helper method called to create an instance of {@link DeserializationContext}\n     * for deserializing a single root value.\n     * Can be overridden if a custom context is needed.\n     */\n    protected DeserializationContextExt _deserializationContext() {\n        return _contexts.createContext(_config, _schema, _injectableValues);\n    }\n\n    protected DeserializationContextExt _deserializationContext(JsonParser p) {\n        return _contexts.createContext(_config, _schema, _injectableValues)\n                .assignParser(p);\n    }","sourceCodeStart":2075,"sourceCodeEnd":2111,"githubUrl":"https://github.com/FasterXML/jackson-databind/blob/a50c7d2a1d57234ac4adf70dbd88ac90db6436e4/src/main/java/tools/jackson/databind/ObjectReader.java#L2075-L2111","documentation":"ObjectReader._verifySchemaType() checks that a FormatSchema (e.g. a CSV schema, Avro schema, YAML schema) is usable by the underlying parser factory before deserialization begins. If the schema's type doesn't match the dataformat the reader is configured for (e.g. a CsvSchema on a JSON JsonMapper's reader), Jackson throws IllegalArgumentException naming both the schema class and the expected format. This prevents a silent wrong-format parse that would produce garbage.","triggerScenarios":"Calling reader.forSchema(csvSchema) on a reader obtained from a JsonMapper; mixing schema objects across dataformat modules (AvroSchema on a YAML reader, etc.); passing a schema loaded generically as FormatSchema without checking the originating module; using a base ObjectMapper instead of the format-specific mapper (CsvMapper, YAMLMapper) when a schema is required.","commonSituations":"Copy-paste wiring where a schema built for one dataformat is reused against a different mapper; autowiring the wrong ObjectMapper bean in a Spring setup with multiple format mappers; upgrading a dataformat module that changed its FormatSchema class so the old instance no longer matches; CSV/Avro/Parquet/Protobuf schemas all being 'FormatSchema' but mutually incompatible.","solutions":["Use the format-specific mapper that owns the schema: CsvMapper for CsvSchema, YAMLMapper for YAMLFactory's schema, etc.","Obtain the schema from the same module/factory as the reader: mapper.schemaFor(...) or mapperFactory.getFormatSchema(...).","Verify schema compatibility before assigning: if (!mapper.tokenStreamFactory().canUseSchema(schema)) fail fast with your own message.","Check that you built the reader from the same JsonMapper/Factory instance that produced the schema, especially in DI containers."],"exampleFix":"// before\nJsonMapper jsonMapper = JsonMapper.builder().build();\nCsvSchema csv = CsvSchema.builder().build();\nObjectReader r = jsonMapper.reader(csv); // throws: CSV schema on JSON reader\n// after\nCsvMapper csvMapper = CsvMapper.builder().build();\nCsvSchema csv = csvMapper.schemaFor(MyType.class);\nObjectReader r = csvMapper.reader(csv);","handlingStrategy":"validation","validationCode":"// Verify schema compatibility before assigning it to a reader\nif (schema != null && !mapper.tokenStreamFactory().canUseSchema(schema)) {\n    throw new IllegalArgumentException(\"schema \" + schema.getClass() + \" not for \" + mapper.tokenStreamFactory().getFormatName());\n}\nObjectReader r = mapper.reader(schema);","typeGuard":"boolean schemaMatches(JsonMapper m, FormatSchema s) {\n    return s != null && m.tokenStreamFactory().canUseSchema(s);\n}","tryCatchPattern":"try {\n    return mapper.reader(schema).readValue(input);\n} catch (IllegalArgumentException e) {\n    if (e.getMessage().startsWith(\"Cannot use FormatSchema\")) {\n        // resolve to the correct format-specific mapper and retry\n    }\n    throw e;\n}","preventionTips":["Always obtain the schema from the same format-specific mapper that will read it.","In DI, qualify mapper beans so the schema-bearing component gets the matching one.","Unit-test schema+reader pairs after module upgrades."],"tags":["object-reader","schema","dataformat","configuration"],"analyzedSha":"a50c7d2a1d57234ac4adf70dbd88ac90db6436e4","analyzedAt":"2026-08-06T20:31:51.404Z","schemaVersion":2},"datasetVersion":"2026-08-07T02:17:10.218Z"}