Could not load type 'ASP.xxx' when referencing a precompiled master page

StackOverflow https://stackoverflow.com/questions/5807209

Question

I'm attempting to precompile a few master pages (not update-able) to share them across multiple applications. The project I'm precompiling is a Web Site. The project that references precompiled assemblies is a Web Application. However, I'm getting a Could not load type 'ASP.xxx_master' every time i try to reference the master page from the client. 

<%@ Master Language="C#" Inherits="ASP.sitebase_master" %>

My precompiled master page looks like this.

<%@ Master Language="C#" ClientIDMode="Static" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org  /TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="AspNetHead" runat="server">
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />   
    <!--[if IE]><meta http-equiv="X-UA-Compatible" content="IE=7" /><![endif]-->
    <asp:ContentPlaceHolder ID="MetaContent" runat="server" />
    <title>Web Portal</title>   
    <link href="/media/css/style.css" rel="stylesheet" type="text/css" />
    <link href="/media/js/plugins/colorbox/colorbox.css" rel="stylesheet" type="text/css" />
    <asp:ContentPlaceHolder ID="StyleContent" runat="server" />
    <script src="https://ajax.googleapis.com/ajax/libs/jquery/1.5.1/jquery.min.js" type="text/javascript" language="javascript"></script>
    <script src="/media/js/plugins/colorbox/jquery.colorbox-min.js" type="text/javascript" language="javascript"></script>
    <script src="/media/js/plugins/filestyle/jquery.filestyle.min.js" type="text/javascript" language="javascript"></script>
    <script src="/media/js/portal.master.js" type="text/javascript" language="javascript"></script>
    <script language="javascript" type="text/javascript">
        PORTAL.debug.init();
        PORTAL.init();
    </script>
    <asp:ContentPlaceHolder ID="ScriptContent" runat="server" />
</head>
<body>
    <div id="hld">  
        <div class="wrapper">
            <form id="AspNetForm" runat="server">
                <asp:ContentPlaceHolder ID="BodyContent" runat="server" />  
            </form>
            <asp:ContentPlaceHolder ID="FooterContent" runat="server" />
        </div>
    </div>
</body>

I'm stumped. No idea why the type isn't resolved. Anybody got suggestions? Both projects (precompiled web site and client web application) are built for ASP.NET 4.0.

EDIT: Here is the list of dependencies of the precompiled assembly. No 3rd party references.

mscorlib, System, System.Web

UDPATE 1

Well, the quick fix to this issue is to specify the full path to the master page. 

<%@ Master Language="C#" Inherits="ASP.sitebase_master, App_Web_sitebase.master.cdcab7d2" %>

After doing that, I'm receiving the following error:

An error occurred while try to load the string resources (FindResource failed with error -2147023083).

After doing some research, this appears to be related to the way HTML markup is parsed within the master page. Not entirely sure yet. I haven't dug much deeper into it. Overall, I can't believe this is the recommended way to share controls as it is absolutely, mindbogglingly idiotic.

UPDATE 2

I couldn't make anything of value out of this. It appears to be hating "script" tags in the head section, but I don't know why. The Master Page works great with a single script include. As soon as i start adding more I keep getting that error. After wasting a full day on this I ended up submitting a bug report to Microsoft. If anyone wants to bump it, please do.

UPDATE 3

I spent a few more days debugging this after no response from MS. Here is my findings. I initially thought that the code generated by CodeDOM provider is looking for a .NET resource that somehow did not get embedded in the assembly when it was published. I was wrong. After some investigation it appears that what's happening is after the Master Page reaches a certain size, a chunk of it is stored in the Resource Table in PE Data Directories section of the assembly. In fact, after looking at the generated assembly in PE resource viewer, i was able to confirm this by finding all my script includes in the Resource Table. Now, here is the actual problem. What's happening is that the CodeDOM provider generates a call to Win32 FindResource to pull that resource from the Resource Table. However, FindResource doesn't work on assemblies in memory, only on disk. So it fails with the above exception. I'm getting close, but still no workaround.

Was it helpful?

Solution

I finally have a workaround. It's not pretty, but it resolves the issue. Apparently using LoadControl to pre-load precompiled MasterPages loads all of the resources that FindResource cannot find otherwise. So, here is all i did to make this work.

In my client application I created a dummy master page (i.e. Dummy.Master) which references my precompiled master page like so:

<%@ Master Language="C#" Inherits="ASP.sitebase_master, App_Web_sitebase.master.cdcab7d2" %>

Now, any .aspx page which references Dummy.Master needs to preload the precompiled MasterPage type like so:

        protected override void OnPreInit(EventArgs e)
        {
            ASP.sitebase_master mp = (ASP.sitebase_master)Page.LoadControl(typeof(ASP.sitebase_master), null);

            base.OnPreInit(e);
        }

I don't know why this works, but it does. This code must run before the MasterPage is resolved, so PreInit worked great. After glancing at the .NET code for a few seconds in Reflector, it appears that LoadControl actually does some assembly compiling voodoo when it attempts to load a certain control type. So perhaps something in there loads that PE resource data section. The best place to put it would be in the base class I suppose which all pages could inherit from. Also, each loaded control (master page in this case) ought to be cached. Here is a good article explaining just that.

Hopefully this helps someone as much as it helped me. It was a pretty big show stopper for me.

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