报错1

RLException: Invalid roslaunch XML syntax: no element found: line 1, column 0
The traceback for the exception was written to the log file

原因

launch文件未保存

解决方法

对文件进行保存，重新进行运行

报错2

RLException: Invalid roslaunch XML syntax: mismatched tag: line 5, column 2
The traceback for the exception was written to the log file

原因

代码格式不对

解决方法

修改代码 第4行最后，缺少了"/"