Base class includes the field 'X', but its type (System.Web.UI.ScriptManager) is not compatible with the type of control (System.Web.UI.ScriptManager)

Question

The full error is

The base class includes the field \'ScriptManager1\', but its type (System.Web.UI.ScriptManager) is not compatible with the type of

Answer 1

We had this same problem when precompiling our application from the command line using the "Application is updatable" flag:

aspnet_compiler.exe -u

removing the -u flag solved this issue. Don't ask me why!