Unable to cast object of type 'ASP.masterpage_master' to type 'MasterPage

[GaryDean]

"Unable to cast object of type 'ASP.masterpage_master' to type 'MasterPage"

This code has always worked but today it is getting the exception in the
subject line of this post...

protected void Page_Load(object sender, EventArgs e)
{

this.Master.HeadingLabel.Text = "Direct 4506 Purchase"; <--this
gets the cast exception

I'm changing a public property in the master page- we do it all the time. I
googled the error and a lot of people were getting it back in 2006 where it
had to do with a caching bug in IIS I think. Why would I suddenly get this
today? I bounced IIS reloaded the project but to no avail.
Thanks,
Gary

[Jialiang Ge [MSFT]]

Hello Gary,

Yes, you are right. I confirmed with the ASP.NET team. The hotfix was
released on 4/12/2007, and it has been included into .NET Framework 2.0 SP1
(See: Problems that are fixed in the .NET Framework 2.0 SP1
http://support.microsoft.com/kb/945757). I think the KB article
http://support.microsoft.com/kb/915782/en-us does need an update to reflect
this. I will file a request to the KB team and ask them to update the
article as soon as possible. Thank you for pointing it out.

The "batch" attribute in the <compilationelement indicates whether
batching is supported. If True (default to be true), eliminates the delay
caused by the compilation when you access a file for the first time.
ASP.NET precompiled all the uncompelled files in a batch mode, which causes
an even longer delay the first time the files are compiled. However, after
this initial delay, this compilation delay is eliminated on subsequent
access of the file. If this attribute is False, we turn off the batch
compilation on the web site. See MSDN article
http://msdn2.microsoft.com/en-us/library/s10awwz0.aspx

I also see a lot of community member say that batch="false" can resolved
the problem:
http://forums.asp.net/t/954194.aspx?PageIndex=7
and Scott Guthrie from Microsoft agreed that it can fix the problem. This
doesn't impact runtime performance. IIS also doesn't recompile when the
application restarts unless there has been a code or configuration change
that requires it - so you won't have performance issues related to that
unless you are making code changes on the live site.

Scott Guthrie has a great blog entry at:
http://weblogs.asp.net/scottgu/archi...x-patch-availa
ble-for-asp-net-compilation-issues.aspx
This explains the resolution of the issue in detail.

If you have any other concern or need anything else, please feel free to
let me know.

Thanks
Jialiang Ge (ji****@online.microsoft.com, remove 'online.')
Microsoft Online Community Support

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