I'm running into the same issue with stable MP 2.3.4.8 and ECP 0.0.3.1.  Did I bork something with the upgrade?  Here's the output from the error log:

2010-08-10 15:17:22,798 ERROR mojoPortal.Web.Global - xxx.xxx.xxx.xxx-en-US - /Events/EditEvent.aspx?mid=208&pageid=0
System.IO.FileLoadException: Could not load file or assembly 'AjaxControlToolkit, Version=3.0.20820.16598, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
File name: 'AjaxControlToolkit, Version=3.0.20820.16598, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e'
at System.Signature._GetSignature(SignatureStruct& signature, Void* pCorSig, Int32 cCorSig, IntPtr fieldHandle, IntPtr methodHandle, IntPtr declaringTypeHandle)
at System.Signature.GetSignature(SignatureStruct& signature, Void* pCorSig, Int32 cCorSig, RuntimeFieldHandle fieldHandle, RuntimeMethodHandle methodHandle, RuntimeTypeHandle declaringTypeHandle)
at System.Signature..ctor(RuntimeFieldHandle fieldHandle, RuntimeTypeHandle declaringTypeHandle)
at System.Reflection.RtFieldInfo.get_FieldType()
at System.Web.UI.Util.GetNonPrivateFieldType(Type classType, String fieldName)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildFieldDeclaration(ControlBuilder builder)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, Boolean topLevelControlInTemplate, PropertyEntry pse)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, Boolean topLevelControlInTemplate, PropertyEntry pse)
at System.Web.Compilation.BaseTemplateCodeDomTreeGenerator.BuildSourceDataTreeFromBuilder(ControlBuilder builder, Boolean fInTemplate, Boolean topLevelControlInTemplate, PropertyEntry pse)
at System.Web.Compilation.TemplateControlCodeDomTreeGenerator.BuildMiscClassMembers()
at System.Web.Compilation.BaseCodeDomTreeGenerator.BuildSourceDataTree()
at System.Web.Compilation.BaseCodeDomTreeGenerator.GetCodeDomTree(CodeDomProvider codeDomProvider, StringResourceBuilder stringResourceBuilder, VirtualPath virtualPath)
at System.Web.Compilation.BaseTemplateBuildProvider.GenerateCode(AssemblyBuilder assemblyBuilder)
at System.Web.Compilation.AssemblyBuilder.AddBuildProvider(BuildProvider buildProvider)

WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].

 

SO, I noticed a weird thing when downloading 2.3.4.8

the zip file marked net40 contains net35 configs and vice versa.  I've tried several combinations, and now now matter how I bake it, I get a 500.19 error, saying that

Module IIS Web Core
Notification Unknown
Handler Not yet determined
Error Code 0x80070032
Config Error The configuration section 'system.web.extensions' cannot be read because it is missing a section declaration
Config File \\?\C:\inetpub\wwwroot\biophysics\web.config
Requested URL http://biop.lsa.umich.edu:80/
Physical Path
Logon Method Not yet determined
Logon User Not yet determined

Also, using the included web.config, and changing out the net4 net40, etc web config files produces the same result.

here's the section in question:

<system.web.extensions>
<scripting>
<scriptResourceHandler enableCompression="true" enableCaching="true"/>
<webServices>
<authenticationService enabled="true" requireSSL="false"/>
<roleService enabled="true"/>
</webServices>
</scripting>
</system.web.extensions>

Thanks for your help again.

Okay, I've gotten it upgraded more or less correctly at this point with your help.  However, now I'm getting the same-ish error for ECP:

System.IO.FileLoadException: Could not load file or assembly 'AjaxControlToolkit, Version=3.5.40412.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
File name: 'AjaxControlToolkit, Version=3.5.40412.0, Culture=neutral, PublicKeyToken=28f01b0e84b6d53e'
at System.Signature.GetSignature(SignatureStruct& signature, Void* pCorSig, Int32 cCorSig, RuntimeFieldHandleInternal fieldHandle, IRuntimeMethodInfo methodHandle, RuntimeType declaringType)

I've used the files from the 4.0 folder in ECP 0.0.3.1 But I'm still getting this.  I know I'm doing something completely idiotic at this point.

One last time?  I'm gonna have to buy you a six-pack.