Could anyone help?

I often got error message when I upgrade the DNN or install a module. Maybe the error message doesn't all the same as my question(But in my experience, all errors can find some words related to module loading fail. ). But my problem is after I change the web.config to the setting I mention before in this thread, this error gone. I suppose this because no problem in the system at all. If there is really a error in my DNN system, error still happened even I changed the web.config.

I feel that DNN will re-do some compile action when I upgrade or install a module but I am not sure. This issue happened when the compile has some problem during it's process. I don't know the reason but I know I can use change web.config to solve this problem. This is very strange. That why I want to know is there a formal solution to this kind issue. I am very afraid some day I can't use change web.config to solve this error.

I changed web.config twice. The final one is the same as the original one. But the error will gone. That what I met now.