Sitecore is not defined in webedit

After a migration to sitecore 6.5, the webedit was always say with a message "loading" and we saw an error message "Sitecore is not defined" a javascript.

To make it short the resolution is really easy: you just need to remove the following code if you had it before the migration

<sc:Placeholder ID="webedit" Key="webedit" runat="server" />

If you want to go a bit deeper into the cause of this error, the javascipt who cause this error is automatically regenerate by sitecore when not exist. If you need to control which codes are inserted into the page when you are in webedit mode you may overide the following configuration. This one have evolve into the version 6.5 and this is the cause of our error.

<pageextender type="Sitecore.Layouts.PageExtenders.WebEditPageExtender" />

Error message - The operation could not be completed

I post here an error message I had yesterday on the sitecore of one of our customer because I don't have found this answer on the sdn site of in the forums.

We had randomly some error messages:

"The operation could not be completed.

Your session may have been lost due to a time-out or a server failure.

Try again."

After investigation, I don't have found any error messages in the logs or in the windows event viewer. But, we had multiple log files with the same datetime.

In fact the resolution was pretty simple the number of worker process of the application pool was set to 5 but it must be set to 1.

To change it:

1. In iis select your application pool and click on the "Advanced settings" button
   
   
2. In the "Process Model" section, set the "Maximum Worker Process" to 1.