Strange question - startProcessInstanceById() cause error

This is my first time asking a question in the forum.flowable.org . Please forgive me if the description is unclear.
这是我第一次在forum.flowable.org提问,如果有描述不清楚的地方请包容

When I request service for the first time, there will be no errors, but I will get an error when I request again
当我第一次请求服务时不会出错,但后续请求就会出现异常

If you can help me, I will be very grateful
如果你能帮助我,我将十分感激

The error occurs in the following code
错误发生在以下代码

ProcessInstance processInstance = runtimeService.startProcessInstanceById(req.getProcessDefinitionId(), req.getBusinessId(), variables);

This is the error log
这是错误日志

org.apache.ibatis.exceptions.PersistenceException: 

Error updating database. Cause: java.sql.SQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (dev_xx.act_ru_task, CONSTRAINT ACT_FK_TASK_EXE FOREIGN KEY (EXECUTION_ID_) REFERENCES act_ru_execution (ID_))

The error may exist in org/flowable/task/service/db/mapping/entity/Task.xml

The error may involve org.flowable.task.service.impl.persistence.entity.TaskEntityImpl.insertTask-Inline

The error occurred while setting parameters

SQL: insert into ACT_RU_TASK (ID_, REV_, NAME_, PARENT_TASK_ID_, DESCRIPTION_, PRIORITY_, CREATE_TIME_, OWNER_, ASSIGNEE_, DELEGATION_, EXECUTION_ID_, PROC_INST_ID_, PROC_DEF_ID_, TASK_DEF_ID_, SCOPE_ID_, SUB_SCOPE_ID_, SCOPE_TYPE_, SCOPE_DEFINITION_ID_, TASK_DEF_KEY_, DUE_DATE_, CATEGORY_, SUSPENSION_STATE_, TENANT_ID_, FORM_KEY_, CLAIM_TIME_, IS_COUNT_ENABLED_, VAR_COUNT_, ID_LINK_COUNT_, SUB_TASK_COUNT_) values (?, 1, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ? )

Cause: java.sql.SQLIntegrityConstraintViolationException: Cannot add or update a child row: a foreign key constraint fails (dev_xx.act_ru_task, CONSTRAINT ACT_FK_TASK_EXE FOREIGN KEY (EXECUTION_ID_) REFERENCES act_ru_execution (ID_))