My program occasionally appears with the following error：
Fatal error: Class CI_Session_files_driver contains 5 abstract method and must therefore be declared abstract or implement the remaining methods.
![[Image: 1523595699WechatIMG176.jpeg]]()
My configuration file is as follows：
![[Image: 1523595699WechatIMG175.jpeg]]()
I've been searching the internet for a long time and I can't find a solution.But I go to the CI of the following system/libraries/Session/drivers found the problem。
This is Session_driver.php
![[Image: 1523596189WechatIMG177.jpeg]]()
this is Session_files_driver.php
![[Image: 1523596189WechatIMG178.jpeg]]()
Why implement this interface twice?I felt this would be a fatal error.I think that's why I've got a fatal error in my project.
May I ask a CI developer to tell me why? Thank you.
Fatal error: Class CI_Session_files_driver contains 5 abstract method and must therefore be declared abstract or implement the remaining methods.
![[Image: 1523595699WechatIMG176.jpeg]](http://noobiepublic.oss-cn-shenzhen.aliyuncs.com/picture/1523595699WechatIMG176.jpeg)
My configuration file is as follows：
![[Image: 1523595699WechatIMG175.jpeg]](http://noobiepublic.oss-cn-shenzhen.aliyuncs.com/picture/1523595699WechatIMG175.jpeg)
I've been searching the internet for a long time and I can't find a solution.But I go to the CI of the following system/libraries/Session/drivers found the problem。
This is Session_driver.php
![[Image: 1523596189WechatIMG177.jpeg]](http://noobiepublic.oss-cn-shenzhen.aliyuncs.com/picture/1523596189WechatIMG177.jpeg)
this is Session_files_driver.php
![[Image: 1523596189WechatIMG178.jpeg]](http://noobiepublic.oss-cn-shenzhen.aliyuncs.com/picture/1523596189WechatIMG178.jpeg)
Why implement this interface twice?I felt this would be a fatal error.I think that's why I've got a fatal error in my project.
May I ask a CI developer to tell me why? Thank you.