在安装完DNN2.1.2后，老是出现An error has occurred writing to the exception log. The permissions are not set properly on the log file or directory, or the log file has been marked as READ-ONLY.错误，请问怎么解决？

An error has occurred writing to the exception log. The permissions are not set properly on the log file or directory, or the log file has been marked as READ-ONLY.错误，请问怎么解决？