njnu-seafish opened a new issue, #17710: URL: https://github.com/apache/dolphinscheduler/issues/17710
### Search before asking - [x] I had searched in the [issues](https://github.com/apache/dolphinscheduler/issues?q=is%3Aissue) and found no similar issues. ### What happened **Master task dispatch failed: encountered a null key in a parameter map, which violates JSON serialization rules; The dolphinscheduler-master.log log file contains a large number of the following error messages**. ` [WI-751315][TI-2077572] - 2025-11-19 17:00:08.610 ERROR [WorkerGroupTaskDispatcher-default] o.a.d.e.b.s.JsonSerializer:[67] - serializeToString exception! com.fasterxml.jackson.databind.JsonMappingException: Null key for a Map not allowed in JSON (use a converting NullKeySerializer?) (through reference chain: org.apache.dolphinscheduler.task.executor.operations.TaskExecutorDispatchRequest["taskExecutionContext"]->org.apache.dolphinscheduler.plugin.task.api.TaskExecutionContext["prepareParamsMap"]->java.util.HashMap["null"]) at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:283) at com.fasterxml.jackson.databind.SerializerProvider.mappingException(SerializerProvider.java:1370) at com.fasterxml.jackson.databind.SerializerProvider.reportMappingProblem(SerializerProvider.java:1266) at com.fasterxml.jackson.databind.ser.impl.FailingSerializer.serialize(FailingSerializer.java:32) at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeFields(MapSerializer.java:791) at com.fasterxml.jackson.databind.ser.std.MapSerializer.serializeWithoutTypeInfo(MapSerializer.java:764) at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:720) at com.fasterxml.jackson.databind.ser.std.MapSerializer.serialize(MapSerializer.java:35) at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:732) at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:772) at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) at com.fasterxml.jackson.databind.ser.BeanPropertyWriter.serializeAsField(BeanPropertyWriter.java:732) at com.fasterxml.jackson.databind.ser.std.BeanSerializerBase.serializeFields(BeanSerializerBase.java:772) at com.fasterxml.jackson.databind.ser.BeanSerializer.serialize(BeanSerializer.java:178) at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider._serialize(DefaultSerializerProvider.java:479) at com.fasterxml.jackson.databind.ser.DefaultSerializerProvider.serializeValue(DefaultSerializerProvider.java:318) at com.fasterxml.jackson.databind.ObjectMapper._writeValueAndClose(ObjectMapper.java:4719) at com.fasterxml.jackson.databind.ObjectMapper.writeValueAsString(ObjectMapper.java:3964) at org.apache.dolphinscheduler.extract.base.serialize.JsonSerializer.serialize(JsonSerializer.java:65) at org.apache.dolphinscheduler.extract.base.StandardRpcRequest.of(StandardRpcRequest.java:42) at org.apache.dolphinscheduler.extract.base.client.SyncClientMethodInvoker.invoke(SyncClientMethodInvoker.java:43) at org.apache.dolphinscheduler.extract.base.client.ClientInvocationHandler.invoke(ClientInvocationHandler.java:56) at com.sun.proxy.$Proxy209.dispatchTask(Unknown Source) at org.apache.dolphinscheduler.server.master.engine.task.client.PhysicalTaskExecutorClientDelegator.dispatch(PhysicalTaskExecutorClientDelegator.java:78) at org.apache.dolphinscheduler.server.master.engine.task.client.TaskExecutorClient.dispatch(TaskExecutorClient.java:54) at org.apache.dolphinscheduler.server.master.engine.task.dispatcher.WorkerGroupDispatcher.doDispatchTask(WorkerGroupDispatcher.java:94) at org.apache.dolphinscheduler.server.master.engine.task.dispatcher.WorkerGroupDispatcher.run(WorkerGroupDispatcher.java:79) [WI-751315][TI-2077572] - 2025-11-19 17:00:08.611 ERROR [WorkerGroupTaskDispatcher-default] o.a.d.s.m.e.t.d.WorkerGroupDispatcher:[102] - Dispatch Task: 2077572 failed will retry after: 60000/ms ` ### What you expected to happen The Master is able to dispatch this task normally ### How to reproduce **Whenever there is a parameter with a null key**. mysql> select id,task_type,workflow_instance_id,task_params from t_ds_task_instance where id = 2077572 \G; *************************** 1. row *************************** id: 2077572 task_type: SHELL workflow_instance_id: 751315 task_params: {"localParams":[],"rawScript":"#!/bin/bash\nset -e\n\n\n \necho \"====================================\"","resourceList":[{"resourceName":"hdfs://xxx/dolphinscheduler/default/resources/123.sql"}]} mysql> select global_params from t_ds_workflow_instance where id = 751315 \G; *************************** 1. row *************************** global_params: [{**"prop":null**,"direct":"IN","type":"VARCHAR","value":""}] ### Anything else _No response_ ### Version dev ### Are you willing to submit PR? - [x] Yes I am willing to submit a PR! ### Code of Conduct - [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct) -- This is an automated message from the Apache Git Service. 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