WIX Installer: Updating existing value in config file

Question

I am new to Wix and up till now I was able to manage it but now I want to update existing value of a Sub node from a config file. Below is my code to update it. But I get the error: failed to find the node.

<Component Id="ServiceIPAndPortSave" Guid="*" Directory="INSTALLFOLDER">
  <CreateFolder/>
    <util:XmlConfig
      Id="UpdateIP"
      On="install"
      File="[INSTALLFOLDER]ProjectName.exe.config"
      Action="create"
      Node="value"  
    ElementPath="//configuration/userSettings/ProjectName.My.MySettings/setting[\[]@name='IPAddres'[\]]/@value"
      Value="[SERVICEIP]"
  />
</Component>

And below is the format for my config file:

<configuration>
<userSettings>
<ProjectName.My.Settings>
<setting name="IPAddres" serializeAs="String">
    <value>127.0.0.1</value>
</setting>
</ProjectName.My.Settings>
</userSettings>
</configuration>

Answer 1

Your XPATH expression is incorrect, you have two problems:

1. Your reference to the ProjectName.My.Settings element is invalid, you are using ProjectName.My.MySettings .
2. Your reference to the value element is invalid, you are using attribute notation.

And while not incorrect, you are rooting the search from anywhere by using // at the start of your query.

Try:

/configuration/userSettings/ProjectName.My.Settings/setting[\[]@name='IPAddres'[\]]/value