I am also having a similar problem with general exception errors:

Message: System.Web.HttpException: Could not load type ''. ---> System.ArgumentException: String cannot have zero length. at System.Reflection.Assembly._GetType(String name, Boolean throwOnError, Boolean ignoreCase) at System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) --- End of inner exception stack trace --- at System.Web.Compilation.BuildManager.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase) at DotNetNuke.Framework.Reflection.CreateType(String TypeName, String CacheKey, Boolean UseCache, Boolean IgnoreErrors)

 and

Message: System.ArgumentNullException: Value cannot be null. Parameter name: type at System.Activator.CreateInstance(Type type, Boolean nonPublic) at DotNetNuke.Framework.Reflection.CreateObject(String TypeName, String CacheKey) at DotNetNuke.Services.Search.ModuleIndexer.GetModuleList(Int32 PortalID

I am getting these errors and I just cannot fathom out how to deal with them.

I see loads of these errors in the Event Log:

I have applied the SQL fix mentioned above (UPDATE DesktopModules SET SupportedFeatures = 0 WHERE SupportedFeatures = -1)

I don't get these errors on my localhost application where I develop the modules, it is only when they are deployed to our staging servers I see the error.

I read somewhere else that it could be a namespace issue.

I checked my manifest file and found there was a problem with the class name as highlighted in bold above. I corrected this and installed a new version of the module.

New module files:

DNN File:

      <businesscontrollerclass>HRG.Modules.ProfileAlert_V2.ProfileAlertController</businesscontrollerclass>
 

Code file

Namespace HRG.Modules.ProfileAlert_V2

    Public Class ProfileAlertController
        Implements Entities.Modules.ISearchable
        Implements Entities.Modules.IPortable
 

Still I got these errors, still referring to to the OLD HRG.Modules.ProfileAlert_V2.ProfileAlert_V2Controller .

So, I have just uninstalled this module (including deleting files), cleared the cache and restarted the application, but again i am STILL seeing this error????????

I have checked the database (all module tables) and every reference to the .ProfileAlert_V2 module has been removed. I have also stopped the app pool and done an iisreset.

What on earth is going on?

Why am I stillgetting errors referencing a class that is no longer installed on the portal????

 I have just found another vaguely similar thread and this recommended switch off the search scheduler, but I have already done that so please don't suggest that as a fix.