How do you modify the web config appSettings at runtime

Question

I am confused on how to modify the web config appSettings values at runtime  For example  I have this appSettings section    lt appSettings gt     lt add key  productspagedesc  value  TODO  Edit this default message    gt     lt add key  servicespagedesc  value  TODO  Edit this default message    gt     lt add key  contactspagedesc  value  TODO  Edit this default message    gt     lt add key  aboutpagedesc  value  TODO  Edit this default message    gt     lt add key  homepagedesc  value  TODO  Edit this default message    gt    lt  appSettings gt    Let s say  I want to modify the  homepagedesc  key at runtime  I tried ConfigurationManager and WebConfigurationManager static classes  but the settings are  read-only   How do I modify appSettings values at runtime   UPDATE  Ok  so here I am 5 years later  I would like to point out that experience has told me  we should not put any configuration that intentionally is editable at runtime in the web config file but instead we should put it in a separate XML file as what one of the users commented below  This will not require any of edit of web config file to restart the App which will result with angry users calling you

User · Answer

And if you want to avoid the restart of the application, you can move out the appSettings section:

<appSettings configSource="Config\appSettings.config"/>

to a separate file. And in combination with ConfigurationSaveMode.Minimal

var config = System.Web.Configuration.WebConfigurationManager.OpenWebConfiguration("~");
config.Save(ConfigurationSaveMode.Minimal);

you can continue to use the appSettings section as the store for various settings without causing application restarts and without the need to use a file with a different format than the normal appSettings section.

User · Answer

2012 This is a better solution for this scenario  tested With Visual nbsp Studio nbsp 2008    Configuration config   WebConfigurationManager OpenWebConfiguration HttpContext Current Request ApplicationPath   config AppSettings Settings Remove  MyVariable    config AppSettings Settings Add  MyVariable    MyValue    config Save      Update 2018    Tested in vs 2015 - Asp net MVC5    var config   System Web Configuration WebConfigurationManager OpenWebConfiguration       config AppSettings Settings  MyVariable   Value    MyValue   config Save      if u need to checking element exist  use this code     var config   System Web Configuration WebConfigurationManager OpenWebConfiguration       if  config AppSettings Settings  MyVariable      null    config AppSettings Settings  MyVariable   Value    MyValue     else   config AppSettings Settings Add  MyVariable    MyValue      config Save

User · Answer

Who likes directly to the point   In your Config       lt appSettings gt        lt add key  Conf id  value  71    gt      lt  appSettings gt    in your code c       SET     ConfigurationManager AppSettings Set  Conf id    whateveryourvalue             GET                   string conf   ConfigurationManager AppSettings Get  Conf id   ToString

User · Answer

You need to use WebConfigurationManager OpenWebConfiguration    For Example   Dim myConfiguration As Configuration   System Web Configuration WebConfigurationManager OpenWebConfiguration      myConfiguration ConnectionStrings ConnectionStrings  myDatabaseName   ConnectionString   txtConnectionString Text myConfiguration AppSettings Settings Item  myKey   Value   txtmyKey Text myConfiguration Save     I think you might also need to set AllowLocation in machine config  This is a boolean value that indicates whether individual pages can be configured using the  element  If the  allowLocation  is false  it cannot be configured in individual  elements    Finally  it makes a difference if you run your application in IIS and run your test sample from Visual Studio  The ASP NET process identity is the IIS account  ASPNET or NETWORK SERVICES  depending on IIS version    Might need to grant ASPNET or NETWORK SERVICES Modify access on the folder where web config resides

User · Answer

Try This   using System  using System Configuration  using System Web Configuration   namespace SampleApplication WebConfig       public partial class webConfigFile   System Web UI Page               protected void Page Load object sender  EventArgs e                          Helps to open the Root level web config file              Configuration webConfigApp   WebConfigurationManager OpenWebConfiguration                     Modifying the AppKey from AppValue to AppValue1             webConfigApp AppSettings Settings  ConnectionString   Value    ConnectionString                 Save the Modified settings of AppSettings              webConfigApp Save

User · Answer

I know this question is old  but I wanted to post an answer based on the current state of affairs in the ASP NET IIS world combined with my real world experience   I recently spearheaded a project at my company where I wanted to consolidate and manage all of the appSettings  amp  connectionStrings settings in our web config files in one central place  I wanted to pursue an approach where our config settings were stored in ZooKeeper due to that projects maturity  amp  stability  Not to mention that fact that ZooKeeper is by design a configuration  amp  cluster managing application   The project goals were very simple    get ASP NET to communicate with ZooKeeper in Global asax  Application Start - pull web config settings from ZooKeeper    Upon getting passed the technical piece of getting ASP NET to talk to ZooKeeper  I quickly found and hit a wall with the following code   ConfigurationManager AppSettings Add key name  data value    That statement made the most logical sense since I wanted to ADD new settings to the appSettings collection  However  as the original poster  and many others  mentioned  this code call returns an Error stating that the collection is Read-Only    After doing a bit of research and seeing all the different crazy ways people worked around this problem  I was very discouraged  Instead of giving up or settling for what appeared to be a less than ideal scenario  I decided to dig in and see if I was missing something    With a little trial and error  I found the following code would do exactly what I wanted   ConfigurationManager AppSettings Set key name  data value    Using this line of code  I am now able to load all 85 appSettings keys from ZooKeeper in my Application Start   In regards to general statements about changes to web config triggering IIS recycles  I edited the following appPool settings to monitor the situation behind the scenes   appPool-- gt Advanced Settings-- gt Recycling-- gt Disable Recycling for Configuration Changes   False appPool-- gt Advanced Settings-- gt Recycling-- gt Generate Recycle Event Log Entry-- gt  For Each Setting    True   With that combination of settings  if this process were to cause an appPool recycle  an Event Log entry should have be recorded  which it was not   This leads me to conclude that it is possible  and indeed safe  to load an applications settings from a centralized storage medium   I should mention that I am using IIS7 5 on Windows 7  The code will be getting deployed to IIS8 on Win2012  Should anything regarding this answer change  I will update this answer accordingly

User · Answer

Changing the web config generally causes an application restart   If you really need your application to edit its own settings  then you should consider a different approach such as databasing the settings or creating an xml file with the editable settings

[asp.net] How do you modify the web.config appSettings at runtime?

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