Mailchimp Connection Error: "Failed to update data source credentials"

Hi Kiyan I know this reply is very late. Since there’s no built-in connector for Mailchimp to PBI anymore, you will have to look for another way. As a workaround, maybe you can use a 3rd party connector, it can save you a lot of time compared to other options. I've tried windsor.ai, supermetrics and funnel.io. I stayed with windsor because it is much cheaper so just to let you know other options. In case you wonder, to make the connection first search for the Mailchimp connector in the data sources list:

After that, you will have to first create a secret API key in your Mailchimp account and then using your credentials add your account to the platform.

Once you’ve done this, you can proceed and go to the “Preview and destination” step

There just select the fields you need. Finally, just select PBI as your data destination and finally just copy and paste the url on PBI --> Get Data --> Web --> Paste the url.