{"record":{"id":"e91cba89b15d5eb1","repo":"apache/flink","slug":"serializer-type-not-specified-for","errorCode":null,"errorMessage":"Serializer type not specified for {}","messagePattern":"Serializer type not specified for (.+?)","errorType":"validation","errorClass":"IllegalArgumentException","httpStatus":null,"severity":"error","filePath":"flink-core/src/main/java/org/apache/flink/api/common/serialization/SerializerConfigImpl.java","lineNumber":408,"sourceCode":"                                Collectors.toMap(\n                                        e ->\n                                                loadClass(\n                                                        e.getKey(),\n                                                        classLoader,\n                                                        \"Could not load class for serialization config\"),\n                                        e -> ConfigurationUtils.parseStringToMap(e.getValue()),\n                                        (v1, v2) -> {\n                                            throw new IllegalArgumentException(\n                                                    \"Duplicated serializer for the same class.\");\n                                        },\n                                        LinkedHashMap::new));\n        for (Map.Entry<Class<?>, Map<String, String>> entry :\n                serializationConfigByClass.entrySet()) {\n            Class<?> type = entry.getKey();\n            Map<String, String> config = entry.getValue();\n            String configType = config.get(\"type\");\n            if (configType == null) {\n                throw new IllegalArgumentException(\"Serializer type not specified for \" + type);\n            }\n            switch (configType) {\n                case \"pojo\":\n                    registerPojoType(type);\n                    break;\n                case \"kryo\":\n                    parseAndRegisterKryoType(classLoader, type, config);\n                    break;\n                case \"typeinfo\":\n                    parseAndRegisterTypeFactory(classLoader, type, config);\n                    break;\n                default:\n                    throw new IllegalArgumentException(\n                            String.format(\n                                    \"Unsupported serializer type %s for %s\", configType, type));\n            }\n        }\n    }","sourceCodeStart":390,"sourceCodeEnd":426,"githubUrl":"https://github.com/apache/flink/blob/2f3c205e9266cb30240eb7f4fdab15cad629a70f/flink-core/src/main/java/org/apache/flink/api/common/serialization/SerializerConfigImpl.java#L390-L426","documentation":"Thrown during parseSerializationConfig when a serialization-config entry for a class has no 'type' key. The 'type' key determines which registration path is used (pojo, kryo, or typeinfo); its absence means the system does not know how to handle the class. Each entry must be a map containing at least a 'type' field.","triggerScenarios":"A serialization-config entry like 'class:com.example.MyType{class:com.example.MyFactory}' where the inner map lacks 'type:typeinfo'. The code reads config.get(\"type\"), gets null, and throws.","commonSituations":"Misunderstanding the config syntax; omitting the required 'type' field; using an old config format that predates the 'type' requirement.","solutions":["Add the 'type' key to the entry with one of: pojo, kryo, or typeinfo.","Consult the serialization-config documentation for the correct map structure.","Validate each config entry has a 'type' key before deployment."],"exampleFix":"# before\npipeline.serialization-config: \"class:com.example.MyType{class:com.example.MyFactory}\"\n\n# after\npipeline.serialization-config: \"class:com.example.MyType{type:typeinfo,class:com.example.MyFactory}\"","handlingStrategy":"validation","validationCode":"// Ensure every serialization-config entry has a 'type' key\nfor (Map.Entry<String, Map<String, String>> e : entries.entrySet()) {\n    if (!e.getValue().containsKey(\"type\")) {\n        throw new IllegalArgumentException(\"Missing 'type' for class: \" + e.getKey());\n    }\n}","typeGuard":null,"tryCatchPattern":null,"preventionTips":["Always include the 'type' key (pojo, kryo, or typeinfo) in each serialization-config entry.","Keep a template config string in documentation for copy-paste correctness."],"tags":["serialization","configuration","parsing","missing-field"],"backgroundTag":null,"analyzedSha":"2f3c205e9266cb30240eb7f4fdab15cad629a70f","analyzedAt":"2026-08-14T08:48:24.518Z","schemaVersion":2},"datasetVersion":"2026-08-14T10:17:34.591Z"}