ERROR : [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified

If you're working with an x64 server, keep in mind that there are different ODBC settings for x86 and x64 applications. The "Data Sources (ODBC)" tool in the Administrative Tools list takes you to the x64 version. To view/edit the x86 ODBC settings, you'll need to run that version of the tool manually:

%windir%\SysWOW64\odbcad32.exe (%windir% is usually C:\Windows)

When your app runs as x64, it will use the x64 data sources, and when it runs as x86, it will use those data sources instead.

I got a similar error, which was resolved by installing the corresponding MySQL drivers from:

http://www.connectionstrings.com/mysql-connector-odbc-5-2/info-and-download/

and by performing the following steps:

1. Go to IIS and Application Pools in the left menu.
2. Select relevant application pool which is assigned to the project.
3. Click the Set Application Pool Defaults.
4. In General Tab, set the Enable 32 Bit Application entry to "True".

Reference:

http://www.codeproject.com/Tips/305249/ERROR-IM-Microsoft-ODBC-Driver-Manager-Data-sou