FinOps Toolkit: DISP_E_TYPEMISMATCH when loading storage reports with data from March 2025

Hi XanB 

It doesn’t really look like a simple bad-file problem in March itself. Based on the behavior you described, it seems more likely that the failure happens during the Analysis Services load, when Power BI tries to materialize a single consistent type across the combined data, rather than during Power Query ingestion. The biggest clue is that March 2025 loads fine on its own, other months load fine together, and the error only appears when March is combined with other months. Also, the same issue was opened today in the FinOps Toolkit GitHub repo and is still untriaged, so this may well be a genuine product edge case rather than something specific to your environment.

One thing that stands out in your diagnostics is that all ftk_Storage columns are ending up as Any.Type. That is often harmless inside Power Query, but it can become a problem later when the model engine has to enforce a single concrete type. In other words, Power Query may tolerate subtle differences that VertiPaq does not.

If I were troubleshooting this further, I would stop focusing on the parquet schema itself, since you already ruled out the obvious mismatches there, and instead force explicit types in the final Costs query before load. I’d start with the usual suspects like date/time fields, decimals, booleans, and nullable columns. If explicit typing does not resolve it immediately, the fastest next step would be to remove columns in halves until the combined March + non-March load succeeds, then narrow it down to the specific offending column and add defensive coercion such as try Number.From(_) otherwise null or try DateTime.From(_) otherwise null.

Your hypothesis about a transition between export implementations is also reasonable from a timing perspective. Microsoft discussed Enhanced Cost Management exports in spring 2025, and the FinOps Toolkit had release activity around that same period, so a March 2025 boundary effect is plausible. But at this stage I would still frame that as a working theory, not a confirmed root cause.