A quick note on Web.config file in the ASP.NET project. It is worth noting that the file is a XML File (read this for more info – https://msdn.microsoft.com/en-us/library/ff400235.aspx )

One issue that hindered my process earlier was that the content in the value has special character it in, particularly, one of my SQL server’s password has a special character in it.

I would have to go and replace them accordingly. For instance, my password is <Password1& (note that < and ” is inclusive), i would have to change it to
<Password1&

You can refer to the list here – https://en.wikipedia.org/wiki/List_of_XML_and_HTML_character_entity_references