error occurred while establishing a connection to SQL Server

Question

If I have my connection string in the web.config like this (added line feeds for better readability):

Answer 1

You've properly escaped the db filename but not the datasource, therefore it tries to connect to a datasource named "(localdb)11.0", which (most likely) doesn't exist.

Try escaping it properly like this:

SqlConnection cn = new SqlConnection("Data Source=(localdb)\\v11.0;"+
"Initial Catalog=MyDB; Integrated Security=True; "+
"MultipleActiveResultSets=True; AttachDbFilename=D:\\Products.mdf");