When using MySQL with Power BI Desktop, you may come across this error:

Value 'preferred' is not of the correct type

 

It seems that this is caused by an incompatibility between Power BI Desktop and a later MySQL Connector Net version. First, check your version:

If you are running the MySQL Connector Net 8.0.11, you may experience the error described above. To resolve the issue, install the older version:

  1. Close Power BI Desktop
  2. Uninstall MySQL Connector Net 8.0.11
  3. Install MySQL Connector Net 6.10.7 (from here)
  4. Open Power BI Desktop
  5. The error “Value ‘preferred’ is not of the correct type” should be resolved, and you can use MySQL with Power BI again