I'm working on a .NET 4 Web site running on IIS 5.1 and use Ajax Control Toolkit 126.96.36.1995 (July 2013).
A Sys.WebForms.PageRequestManagerServerErrorException exception is thrown after a period of inactivity (or a forced iisreset) and clicking a server Button in a custom control. The Button is inside an UpdatePanel and the latter is inside a TabContainer.
30|error|500|Script entries not loaded yet.|
Script entries not loaded yet.
The exception is not thrown if I use Ajax Control Toolkit 188.8.131.527 (June 2013).