In the course of development we found it necessary to migrate an old user setting into a new one and to then remove it. This brought with it a few problems which I hope to shed some light on below.

In order to get the value of the old setting we used the Property.Settings.GetPreviousVersion() method. Initially we were getting a SettingsPropertyNotFoundException() although the setting was verifiably present in the user.config file. As it turns out we had removed the Property from the Settings designer which removed the Property in the Property.Settings class. In order for Settings to be found, they have to have a property that is tagged with the [UserScopedSettingAttribute] attribute. This tells the GetPreviousVersion() method to look for the setting in user.config. So far so good…

At this point however, the base.Upgrade() method is called to move old settings into the new file. This causes the old, unwanted setting to be moved in right along with all the old settings that we want to keep around. In order to avoid this behavior the [NoSettingsVersionUpgrade] attribute must also be used for the unwanted Property.

public override void Upgrade()
{
string lastConfigFilePath = (string) GetPreviousVersion(”LastConfigFilePath”);
base.Upgrade(); // bring forward our properties that are the
//  same (but also will bring forward LastConfigFilePath)
}

[UserScopedSettingAttribute]
[DebuggerNonUserCode]
[DefaultSettingValueAttribute(”")]
[Obsolete(”Please use MruConfigFilePaths instead”)]
[NoSettingsVersionUpgrade]
public string LastConfigFilePath
{
get
{
throw new NotSupportedException(”LastConfigFilePath is obsolete”);
}
set
{
throw new NotSupportedException(”LastConfigFilePath is obsolete”);
}
}