DataSource.Error: Web.Contents failed to get contents from URL (431): Request Header Fields Too Larg

Hi danielcontente were you able to find a solution? As a workaround, maybe you can try to test your connection with a 3rd party connector. 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 Salesforce connector in the data sources list:

After that, just grant access to your Salesforce account using your credentials, then on preview and destination page you will see a preview of your Salesforce fields:

There just select the fields you need. It is also compatible with custom fields and custom objects, so you'll be able to export them through windsor.  Finally, just select PBI as your data destination and finally just copy and paste the url on PBI --> Get Data --> Web --> Paste the url.