Archives / 2023 / March
  • A breaking change in .NET argument exception message formatting

    A quick reference post about an interesting change in the way .NET formats argument exception messages. This tripped me up when debugging a test that was failing on .NET Core / 6.0 whereas it had been passing forever and still passes on .NET Framework / 4.7. The test was expecting a specific error message. Because .NET Core apparently has changed the format string used for argument exception messages, that expectation was broken.