设置Web.config ，用以上传大于4M文件

Open your Web.config file, and just below the <system.web> tag, add the following tag:

<httpRuntime 
executionTimeout="90" 
maxRequestLength="40960" 
useFullyQualifiedRedirectUrl="false" 
minFreeThreads="8" 
minLocalRequestFreeThreads="4" 
appRequestQueueLimit="100" 
enableVersionHeader="true"
/>

40960 可为 8192 for 8 Mb, 16384 for 16 Mb, 65536 for 64 Mb等等