FileUpload page Jump cannot find the solution to the original page

Do a upload image function, before doing all right, completely can be achieved, but later when the time, as long as the FileUpload control inside the word (select the picture), then press button. It altogether does not perform the Button1_Click event, the direct page jumps, and then displays the page cannot be found. But if the fileupload is empty, it will be executed. What's going on here???
Take care of yourself. Is the reason for uploading the default size of 1M. Just change it in the config file, okay ?
Here's how to modify it:
You can change the limit of the size of the uploaded file
Add the following code to <system.web> </system.web> in Web. config:
Usefullyqualifiedredirecturl= "true" minfreethreads= "8"
Minlocalrequestfreethreads= "4" apprequestqueuelimit= "enableversionheader=" "true"/>
Explain:
HttpRuntime is to configure the ASP. NET HTTP runtime settings to determine how to handle requests to an ASP.
Executiontimeout: Represents the maximum time limit allowed to execute a request, in seconds
maxRequestLength: Indicates the maximum file upload size supported by ASP. This restriction can be used to prevent denial of service attacks that result from the user passing a large number of files to the server. The specified size is in kilobytes. The default value is 4096 KB (4 MB).
It looks like the biggest can be changed to 2G, you look at it.

FileUpload page Jump cannot find the solution to the original page