A Trivial Breaking Change in .NET Framework 4 (Undocumented)

expected result:

System.Exception: outer ---> (overridden)
  --- End of inner exception stack trace ---

actual result in .net framework 4:

System.Exception: outer ---> MyException: inner
  --- End of inner exception stack trace ---

see

• Exception.ToString Method(.NET Framework Class Library)
• .NET Framework 4 Migration Issues

大したことないって？本当に？