How to fix The ConnectionString property has not been initialized

Question

When I start my application I get   The ConnectionString property has not been initialized    Web config    lt connectionStrings gt       lt add name  MyDB           connectionString  Data Source localhost sqlexpress Initial Catalog mydatabase User Id myuser Password mypassword     gt   lt  connectionStrings gt    The stack being   System Data SqlClient SqlConnection PermissionDemand    4876643 System Data SqlClient SqlConnectionFactory PermissionDemand DbConnection outerConnection   20 System Data ProviderBase DbConnectionClosed OpenConnection DbConnection outerConnection  DbConnectionFactory connectionFactory   117 System Data SqlClient SqlConnection Open    122   I m fairly new to  NET and I don t get this one  I found a lot of answers on Google  but none really fixed my issue   What does that mean  Is my web config bad  Is my function bad  Is my SQL configuration not working correctly  I m using sqlexpress    My main problem here is that I m not sure where to start to debug this    anything would help   EDIT    Failling code   MySQLHelper ExecuteNonQuery  ConfigurationManager AppSettings  ConnectionString    CommandType Text  sqlQuery  sqlParams     sqlQuery is a query like  select   from table   sqlParams is not relevant here   The other problem here is that my company uses MySQLHelper  and I have no visibility over it  only have a dll for a helper lib   It has been working fine in other projects  so I m 99  that the error doesn t come from here    I guess if there s no way of debuging it without seeing the code I ll have to wait to get in touch with the person who created this helper in order to get the code

User · Answer

You get this error when a datasource attempts to bind to data but cannot because it cannot find the connection string. In my experience, this is not usually due to an error in the web.config (though I am not 100% sure of this).

If you are programmatically assigning a datasource (such as a SqlDataSource) or creating a query (i.e. using a SqlConnection/SqlCommand combination), make sure you assigned it a ConnectionString.

var connection = new SqlConnection(ConfigurationManager.ConnectionStrings[nameOfString].ConnectionString);

If you are hooking up a databound element to a datasource (i.e. a GridView or ComboBox to a SqlDataSource), make sure the datasource is assigned to one of your connection strings.

Post your code (for the databound element and the web.config to be safe) and we can take a look at it.

EDIT: I think the problem is that you are trying to get the Connection String from the AppSettings area, and programmatically that is not where it exists. Try replacing that with ConfigurationManager.ConnectionStrings["ConnectionString"].ConnectionString (if ConnectionString is the name of your connection string.)

User · Answer

Referencing the connection string should be done as such   MySQLHelper ExecuteNonQuery  ConfigurationManager ConnectionStrings  MyDB   ConnectionString  CommandType Text  sqlQuery  sqlParams     ConfigurationManager AppSettings  ConnectionString   would be looking in the AppSettings for something named ConnectionString  which it would not find  This is why your error message indicated the  ConnectionString  property has not been initialized  because it is looking for an initialized property of AppSettings named ConnectionString   ConfigurationManager ConnectionStrings  MyDB   ConnectionString instructs to look for the connection string named  MyDB    Here is someone talking about using web config connection strings

User · Answer

Use    instead of    as below example   SqlDataAdapter adapter   new SqlDataAdapter sql  ConfigurationManager ConnectionStrings  FADB ConnectionString   ConnectionString               DataTable data   new DataTable                DataSet ds   new DataSet

User · Answer

The connection string is not in AppSettings   What you re looking for is in   System Configuration ConfigurationManager ConnectionStrings  MyDB

User · Answer

I found that when I create Sqlconnection   new SqlConnection    I forgot to pass my connectionString variable  So that is why I changed the way I initialize my connectionString  and nothing changed   And if you like me just don t forget to pass your string connection into SqlConnection parameters  Sqlconnection   new SqlConnection  quot ConnString quot

User · Answer

I stumbled in the same problem while working on a web api Asp Net Core project  I followed the suggestion to change the reference in my code to   ConfigurationManager ConnectionStrings  NameOfTheConnectionString   ConnectionString   but adding the reference to System Configuration dll caused the error  Reference not valid or not supported      To fix the problem I had to download the package System Configuration ConfigurationManager using NuGet  Tools -  Nuget Package-  Manage Nuget packages for the solution

User · Answer

Simply in Code Behind Page use -  SqlConnection con   new SqlConnection  Data Source   DellPC  Initial Catalog   Account  user   sa  password   admin      It Should Work Just Fine

[c#] How to fix "The ConnectionString property has not been initialized"

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