可能是 JSON 文件格式不正确或文件中的配置项有误导致的错误。需要按照文档要求正确配置 JSON 文件，包括源端和目标端的连接信息、任务类型、映射关系等。同时，可以使用 AWS DMS 控制台上的 Task Assessment Report 查看 JSON 文件中的问题，并及时进行修复。

示例代码如下：

{
    "rules": [
        {
            "rule-type": "transformation",
            "rule-id": "1",
            "rule-name": "prepare",
            "rule-action": "prepare-mapping",
            "operand-type": "table",
            "apply": "insert,update",
            "rule-target": "schema.table",
            "input-columns": [],
            "output-width": [
                {
                    "target": "column1",
                    "type": "varchar",
                    "length": 50
                },
                {
                    "target": "column2",
                    "type": "varchar",
                    "length": 100
                }
            ],
            "transformation-rules": [
                {
                    "rule-type": "selection",
                    "rule-id": "2",
                    "rule-name": "select",
                    "operator": "or",
                    "rules": [
                        {
                            "rule-type": "comparison",
                            "rule-id": "3",
                            "rule-name": "compare1",
                            "source": "column1",
                            "target": "constant_value",
                            "operator": "=",
                            "value": "test"
                        }
                    ]
                }
            ]
        }
    ]
}