Why can't i see a detailed error message in this aspx page?

问题

I have a aspx page and it displays custom error but i can't see a detailed error message. My web.config looks like this,

<?xml version="1.0"?>
    <configuration>
    <appSettings />
    <connectionStrings />
    <system.web>
        <compilation debug="true" />
        <authentication mode="Windows" />
        <customErrors mode="On" />
    </system.web>
</configuration>

回答1:

To see the error you need customErrors off, like this:

<customErrors mode="Off"></customErrors>

From the docs, here are the options for the mode attribute:

• On - Specifies that custom errors are enabled. If no defaultRedirect attribute is specified, users see a generic error. The custom errors are shown to the remote clients and to the local host.
• Off - Specifies that custom errors are disabled. The detailed ASP.NET errors are shown to the remote clients and to the local host.
• RemoteOnly - Specifies that custom errors are shown only to the remote clients, and that ASP.NET errors are shown to the local host. This is the default value.

Warning

Setting Off on a live-production site is very risky as some error messages might compromise sensitive data on your site (like code and paths maybe even passwords).

来源：https://stackoverflow.com/questions/3414103/why-cant-i-see-a-detailed-error-message-in-this-aspx-page