Formula firewall error - possible bug

[vitaly]

We are getting the error message "Formula.Firewall: Query '[Query Name]' (step '[Step Name]') references other queries or steps, so it may not directly access a data source. Please rebuild this data combination."

This error appears in a step that merges two local Excel files. Both Excel files' source paths are parametrized. The privacy levels for both data sources are at defaults (we've also tried Organizational and Public). The global and user-file privacy levels are also at defaults.

We've come across a few workarounds:

1) Removing parametrization of source file paths resolves the error.

2) Setting the global privacy level to "Always Ignore Privacy Level Settings" resolves the error.

3) Setting the user-file level privacy level to "Ignore the Privacy Levels and potentially improve performance" resolves the error.

What may be causing the firewall error to be triggerred in this case?

[Anonymous]

See Ken Puls's blog Power Query Errors: Please Rebuild This Data Combination for a workaround that sets up the external query as a function.  Why you have to trick PBI like this I'm not sure...

[vitaly]

Yes, I've seen that post. The question is, why is the formula firewall activating in the first place in our scenario? It sure seems like a bug to me.

[Anonymous]

I think's it's supposed to be a feature rather than a bug, designed to prevent inadvertant security breaches - per https://social.msdn.microsoft.com/Forums/en-US/69153a6d-2205-4456-bcac-3a4689c787cf/parameterising-q...

"we have tried to optimize for the non-advanced user to do things easily and also protect them from cases like the above. For the more advanced user scenarios, they may need to go a bit off the happy path to make the scenario work, such as enabling this non-default mode."

I agree the product could be more helpful than just presenting "Formula firewall error"...  Add as an Idea?

[vitaly]

Sorry, this just does not make sense to me. What security risks are there if the data sources are all local and are marked as such in their respective privacy settings? Everything is in the same folder on the same local disk.

There must be a specific condition that triggers the firewall in this instance. I've reviewed that MSDN forum thread linked to the last reply and Miguel's response does not cover the scenario we encounter. Again, I am familiar with both the intention of the formula firewall and the privacy controls - it's just that these intentions does not appear to be applied properly in our instance.

[Anonymous]

@vitaly,

Without seeing your query, I'm assuming that the error "Query '[Query Name]' (step '[Step Name]') references other queries or steps, so it may not directly access a data source" means you are referencing an internal query and an external data source in the one query?

My reading of the posts I referenced is that the "Formula Firewall" isolates by default ALL external sources as a design, not a bug, even if not as flexible or intuitive as it could be.

[vitaly]

@Anonymous,

We are just referencing those Excel files within the queries. There are no other data sources.

What is the definition of "external sources" in this context? If the Formula Firewall blocked all external sources, would that not make the related privacy settings meaningless?

[Anonymous]

@vitaly,

It may be simpler if you can post your query and maybe some sample data?

Cheers,

Steve.