AstarPathUpdateWindow.cs line
93 says
EditorPrefs.SetString(“AstarRemindUpdateDate”, DateTime.UtcNow.AddDays(7).ToString().ToString(System.Globalization.CultureInfo.InvariantCulture));
Commenting out the last ToString fixes the problem.
EditorPrefs.SetString("AstarRemindUpdateDate", DateTime.UtcNow.AddDays(7).ToString()/*.ToString(System.Globalization.CultureInfo.InvariantCulture)*/);