ERROR [IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified
Symptom: When trying to import data from Excel file the following error message is displayed: ERROR [IM002] [Microsoft][ODBC Driver Manager] Data source name not found and no default driver specified.
Explanation: This error is related to the fact that you have 32-bit ODBC drivers which are not compatible with 64-bit Import Tool.
Solution: You have to use 32-bit version of the Import Tool instead. There should be a shortcut in the Start Menu or simply go to C:\Program Files\Dynamics Professional Solutions\ImportTool and run ImportTool_x86.exe. 32-bit version of the Import Tool is exactly the same as 64-bit version and fully compatible with 64-bit version of the CRM. The only difference is that you can use 32-bit ODBC drivers. This is known limitation of the ODBC drivers.
The other option is to install 64 bit Microsoft Access Data Engine: https://www.microsoft.com/download/details.aspx?id=13255. The download includes both Access and Excel drivers.