Data Privacy and the Formula Firewall in Power BI / Power Query
Have you ever received any Errors similar to these?
Formula.Firewall: Query ‘Merge1’ (step ‘Source’) is accessing data sources that have privacy levels which cannot be used together. Please rebuild this data combination.
Formula.Firewall: Query ‘Query1’ (step ‘Added Custom’) references other queries or steps, so it may not directly access a data source. Please rebuild this data combination.
This is the blog post where I’ll cover this specific topic to answer 3 questions:
- WHY does it even exist
- What triggers this error
- How to better spot the cause of the error
Before we start…let’s define one concept / feature:
Excel specialist turned into BI specialist using the latest tools from Microsoft for BI – Power BI. He is the co-author of ‘M is for Data Monkey’, blogger and also Youtuber of powerful Excel video Tricks.
He has been recognized as a Microsoft Most Valuable Professional (MVP), is a Microsoft Certified Professional (MCP – MCSA: BI Reporting), a Microsoft Certified Trainer (MCT), and is one of the international pioneers in Power Pivot, Power Query and Power BI.