脚本错误Sys.WebForms.PageRequestManager为空或不是对象

作者: Robin 分类: Asp.net 发布时间: 2010-09-25 14:26

原文

http://weblogs.asp.net/chrisri/archive/2007/02/02/demystifying-sys-is-undefined.aspx

Are you running into this error on your ASP.NET AJAX enabled web
site? Does it only happen on some machines or on some browsers? Here’s
how you can get to the bottom of it.

Here’s a little background on what is happening…

When
you have a ScriptManager on a page, ASP.NET AJAX will render a few
script tags to load the various ASP.NET AJAX Scripts, and some inline
script to get everything initialized and running. If you view source on
the page as rendered by your browser, you should see something like
this:

<script type=”text/javascript”>
Sys.WebForms.PageRequestManager._initialize(‘ScriptManager1’, document.getElementById(‘form1’));
Sys.WebForms.PageRequestManager.getInstance()._updateControls([], [], [], 90);
</script>

When
the browser goes to run that code, it’s going to expect
Sys.WebForms.PageRequestManager to be defined somewhere. That somewhere
happens to be in the other scripts that are loaded from script tags
that look like this:

<script src=”/MyWebApp/ScriptResource.axd?[snip – long query string]” type=”text/javascript”></script>

If
the browser fails to load those scripts, the script engine can’t find
the definition for Sys, Sys.WebForms, Sys.WebFormsPageRequestManager,
and thus the error.

So why would those scripts fail to load? We’ve seen several reasons:

1. The browser fails to load the compressed script

This is usually the case if you get the error on IE6, but not on other browsers.

The
Script Resource Handler – ScriptResource.axd compresses the scripts
before returning them to the browser. In pre-RTM releases, the handler
did it all the time for all browsers, and it wasn’t configurable. There
is an issue in one of the components of IE6 that prevents it from
loading compressed scripts correctly. See KB article here.
In RTM builds, we’ve made two fixes for this. One, we don’t compress if
IE6 is the browser client. Two, we’ve now made compression
configurable. Here’s how you can toggle the web.config.

How do
you fix it? First, make sure you are using the AJAX Extensions 1.0 RTM
release. That alone should be enough. You can also try turning off
compression by editing your web.config to have the following:

<system.web.extensions>
<scripting>
<scriptResourceHandler enableCompression=”false” enableCaching=”true” />
</scripting>
</system.web.extensions>

2. The required configuration for ScriptResourceHandler doesn’t exist for the web.config for your application

Make
sure your web.config contains the entries from the default web.config
file provided with the extensions install. (default location:
C:\Program Files\Microsoft ASP.NET\ASP.NET 2.0 AJAX
Extensions\v1.0.61025)

3. The virtual directory you are using for your web, isn’t correctly marked as an application (thus the configuration isn’t getting loaded) – This would happen for IIS webs.

Make sure that you are using a Web Application, and not just a Virtual Directory 

4. ScriptResource.axd requests return 404

This
usually points to a mis-configuration of ASP.NET as a whole. On a
default installation of ASP.NET, any web request to a resource ending
in .axd is passed from IIS to ASP.NET via an isapi mapping.
Additionally the mapping is configured to not check if the file exists.
If that mapping does not exist, or the check if file exists isn’t
disabled, then IIS will attempt to find the physical file
ScriptResource.axd, won’t find it, and return 404.

You can
check to see if this is the problem by coipy/pasting the full url to
ScriptResource.axd from here, and seeing what it returns

<script src=”/MyWebApp/ScriptResource.axd?[snip – long query string]” type=”text/javascript”></script>

How
do you fix this? If ASP.NET isn’t properly installed at all, you can
run the “aspnet_regiis.exe” command line tool to fix it up. It’s
located in C:\WINDOWS\Microsoft.Net\Framework\v2.0.50727. You can run
“aspnet_regiis -i -enable”, which does the full registration of ASP.NET
with IIS and makes sure the ISAPI is enabled in IIS6. You can also run
“aspnet_regiis -s w3svc/1/root/MyWebApp” to only fix up the
registration for your web application.

最后我是通知修复iis 才得以解决的。C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis.exe -i -enable

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