Visual Studio 2017 the connection string could not be found in application settings

Question

For connection database and reading data, I am using a dataset which read connection string from Web.config file. Everything working in Visual Studio 2013. But when I opened

Answer 1

This is a TableAdapter error. TableAdapters provide communication between your application and a database. Some people alleged that seems The Visual Studio 15.8.x no longer uses the connection string in the web.config while you may have not any problem in prior versions like 15.7.x.

Any way I believe you can reproduce a working one by using one of approaches listed in How to: Save and edit connection strings.