Edit App.Config at runtime : C#

Config file will look like – 


<add key=”Applications” value=”Proj1|Proj2|App1|App2|App3″/>


C# code will like this – 

Configuration config = ConfigurationManager.OpenExeConfiguration(ConfigurationUserLevel.None);

AppSettingsSection configSection = config.AppSettings;

if (configSection != null)
if (configSection.IsReadOnly() == false && configSection.SectionInformation.IsLocked == false)
configSection.Settings[“KEY”].Value += “|NewValue”;
catch (ConfigurationException ex)
MessageBox.Show(ex.Message, “Configuration Error”, MessageBoxButtons.OK, MessageBoxIcon.Error);


4 thoughts on “Edit App.Config at runtime : C#

    1. MrNoOne, We are using this code in multiple projects and works fine, so if you can share snapshot of your code, I will try to look at it … It looks like there will be very minor things. You didn’t mentioned how your config file look like and code… It’s little rough to just say ‘DOES NOT WORK…’ & In capital letters…


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