{"record":{"id":"4e92a2cd1e3016a5","repo":"apache/flink","slug":"could-not-access-the-fields-of-the-user-defined-cl","errorCode":null,"errorMessage":"Could not access the fields of the user defined class while checking for serializability.","messagePattern":"Could not access the fields of the user defined class while checking for serializability\\.","errorType":"exception","errorClass":"RuntimeException","httpStatus":null,"severity":"error","filePath":"flink-core/src/main/java/org/apache/flink/api/common/operators/util/UserCodeObjectWrapper.java","lineNumber":114,"sourceCode":"                                \"User-defined object \"\n                                        + userCodeObject\n                                        + \" (\"\n                                        + userCodeObject.getClass().getName()\n                                        + \") contains non-serializable field \"\n                                        + f.getName()\n                                        + \" = \"\n                                        + f.get(current));\n                    }\n                }\n                current = newCurrent;\n            }\n        } catch (NonSerializableUserCodeException e) {\n            // forward those\n            throw e;\n        } catch (Exception e) {\n            // should never happen, since we make the fields accessible.\n            // anyways, do not swallow the exception, but report it\n            throw new RuntimeException(\n                    \"Could not access the fields of the user defined class while checking for serializability.\",\n                    e);\n        }\n    }\n\n    @Override\n    public T getUserCodeObject(Class<? super T> superClass, ClassLoader cl) {\n        return userCodeObject;\n    }\n\n    @Override\n    public T getUserCodeObject() {\n        return userCodeObject;\n    }\n\n    @Override\n    public <A extends Annotation> A getUserCodeAnnotation(Class<A> annotationClass) {\n        return userCodeObject.getClass().getAnnotation(annotationClass);","sourceCodeStart":96,"sourceCodeEnd":132,"githubUrl":"https://github.com/apache/flink/blob/2f3c205e9266cb30240eb7f4fdab15cad629a70f/flink-core/src/main/java/org/apache/flink/api/common/operators/util/UserCodeObjectWrapper.java#L96-L132","documentation":"Error \"Could not access the fields of the user defined class while checking for serializability.\" thrown in apache/flink.","triggerScenarios":"Triggered at runtime when the operation fails because: Could not access the fields of the user defined class while checking for serializability.","commonSituations":"Commonly caused by misconfiguration, missing dependencies or files, unsupported types or operations, or invalid user input leading to: Could not access the fields of the user defined class while checking for serializability.","solutions":["Address the cause reported by the error message: Could not access the fields of the user defined class while checking for serializability.","Verify the inputs, configuration values, and classpath/dependency setup related to this operation, then retry."],"exampleFix":"Correct the condition described (\"Could not access the fields of the user defined class while checking for serializability.\") and rerun the job or command.","handlingStrategy":null,"validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"analyzedSha":"2f3c205e9266cb30240eb7f4fdab15cad629a70f","analyzedAt":"2026-08-14T08:48:24.518Z","schemaVersion":2},"datasetVersion":"2026-08-14T10:17:34.591Z"}