The platform does not know how to deserialize an object of type Microsoft.SharePoint.SPWeb

Hi all,

I have very weird error when I was developing a timer job.
Let me show how I had successfully provision a timer job in WebApplication socpe and changed the different scope (Web) of timer job which totally screwed my SharePoint instance.

This is working code : (WebApplication Scope)

class AlertNotificationInstaller : SPFeatureReceiver
{

private const string JobNameDaily =
ChecklistsConstants.JobNameDaily;
private const string JobNameWeekly =
ChecklistsConstants.JobNameWeekly;


public override void FeatureActivated(SPFeatureReceiverProperties properties)
{
SPWebApplication webApp =
properties.Feature.Parent as SPWebApplication;
if (webApp == null)
throw new SPException("Error obtaining refrence to the Web application.");

#region Delete other Job Definition for System Checklists
foreach (var job in webApp.JobDefinitions)
{
if (job.Name == JobNameDaily)
{
job.Delete();
}

if (job.Name == JobNameWeekly)
{
job.Delete();
}

}
#endregion



#region Create instances for timer jobs
AlertNotificationJob dailyJob = new AlertNotificationJob(JobNameDaily, webApp);
dailyJob.Properties.Add("Daily Job", "Tools");

AlertNotificationJob weeklyJob = new AlertNotificationJob(JobNameWeekly, webApp);
weeklyJob.Properties.Add("Weekly", "Tools");

#endregion

#region Daily


SPDailySchedule daily = new SPDailySchedule();
daily.BeginHour = 10;
daily.BeginMinute = 28;
daily.BeginSecond = 00;

daily.EndHour = 10;
daily.EndMinute = 30;
daily.EndSecond = 00;
dailyJob.Schedule = daily;
dailyJob.Update();



#endregion

#region Weekly

//SAME CODE FOR weekly schedule SPWeeklySchedule


#endregion


}


}

But need to change the time job to the web scope and changed the code as follows:

class AlertNotificationInstaller : SPFeatureReceiver
{

private const string JobNameDaily = ChecklistsConstants.JobNameDaily;
private const string JobNameWeekly = ChecklistsConstants.JobNameWeekly;

private SPWeb web = null;
private SPSite site = null;
public override void FeatureActivated(SPFeatureReceiverProperties properties)
{

web = properties.Feature.Parent as SPWeb;
site = web.Site;
if (web == null)
throw new SPException("Error obtaining refrence to the Web .");

#region Delete other Job Definition for System Checklists
foreach (var job in site.WebApplication.JobDefinitions)
{
if (job.Name == JobNameDaily)
{
job.Delete();
}

if (job.Name == JobNameWeekly)
{
job.Delete();
}

}
#endregion

#region Create instances for timer jobs
AlertNotificationJob dailyJob = new AlertNotificationJob(JobNameDaily,site.WebApplication);
dailyJob.Properties.Add("Daily Job", "Tools");

AlertNotificationJob weeklyJob = new AlertNotificationJob(JobNameWeekly, site.WebApplication);
weeklyJob.Properties.Add("Weekly", "Tools");

#endregion

#region Daily

SPDailySchedule daily = new SPDailySchedule();
daily.BeginHour = 10;
daily.BeginMinute = 28;
daily.BeginSecond = 00;

daily.EndHour = 10;
daily.EndMinute = 30;
daily.EndSecond = 00;
dailyJob.Schedule = daily;
dailyJob.Update();

#endregion

#region Weekly

//Weekly Schedule 

#endregion

}
}

And I did some code chnages as follows:

>> In the feature.xml, I changed the scope from "WebApplication" to "Web".

Scope="WebApplication" to Scope="Web"

>> In Execute method, I changed the scope of "WebApplication" to just "Web"

// get a reference to the current web application
SPWebApplication webApplication = this.Parent as SPWebApplication; TO

// get a reference to the current web application
SPWeb web= this.Parent as SPWeb;

I just upgraded the solution and timer job was provisioned in the web scope.
But when I deactivate this feature I got this error:

The platform does not know how to deserialize an object of type Microsoft.SharePoint.SPWeb. The platform can deserialize primitive types such as strings, integers, and GUIDs; other SPPersistedObjects or SPAutoserializingObjects; or collections of any of the above. Consider redesigning your objects to store values in one of these supported formats, or contact your software vendor for support.


There few other observations:

1) I try the my deactivate the feature on the web scope (through UI) , it threw the same error.
2) Tried uninstall the solution through WSPBuider, it threw this error:

i) Error while killing the timer jobs
ii) Same error mentioned above.

3) Tried delete the solution from Central Admin . Same Error.
4) When I went to Central Admin >> Operations >> Timer Job Definitions and clicked on it, threw this error:


ERROR:

The platform does not know how to deserialize an object of type Microsoft.SharePoint.SPWeb. The platform can deserialize primitive types such as strings, integers, and GUIDs; other SPPersistedObjects or SPAutoserializingObjects; or collections of any of the above. Consider redesigning your objects to store values in one of these supported formats, or contact your software vendor for support.

Now, I have noticed that all the Times Job definitions are screwed up.

I also researched and found that one person had same issue and workaround:
Issue and workaround .


I referred to one the blog which discussed this issue.
http://jritmeijer.spaces.live.com/blog/cns!8A48A27460FB898A!1176.entry

Apparently, SharePoint UI cant help . I have to modify the Database (SharePoint Configuration database ).
After studying the schema of the Config Database, SharePoint uses Hierarchical Object Store (HOS).

There are 2 important tables
1) Classes
2) Objects

What I queried the tables (Classes and Objects) and identified the "corrupt" object. (its the name of the solution , in my case)

>> Deleted the corrupt object . (Objects table)
>> Delete the corresponding class. (Classes table)

Went to Central Admin >> Operations >> Timer Job Definitions .

VOILA!!!

It worked....

I got my lesson and bottom line is that:

>> Whenever you are changing the scope, you MUST DEACTIVATE the feature first and then upgrade the solution. Otherwise, it will screw the SharePoint instance.

Cheers
--Aroh