Power Pivot Data Model refresh goes error after recent Window update on 10-Sep

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Power Pivot Data Model refresh goes error after recent Window update on 10-Sep

PNg-5441 45

Hi everyone,

After a window update on 10-Sep-25, after clicking refresh connection ( from Excel table ) to Data model and Power query that is loaded to Data model. Excel sends a message as below that seems to notice that the refresh is not successful:

"The query did not run or the Data Model could not be accessed. Here's the error message we got: Query optimizer generated too many subcubes in the query plan. "

My files have worked well for months and there were no change since the last successful refresh. I doubt that the window update has done something that leads to this issue.

Despite of this message, I've figured out that my CUBE functions still work well and query the latest updated data. However, the pivot tables that I get from the Data model do not. I can not refresh existing pivot tables to update the latest data as well as can not re-create the same pivot tables from the Data model. As I drag more fields to re-create the pivot tables, excel send me the error message as above.

Is there anyone have any idea of the root cause? How can I fix this error without re-creating the whole file which have the data processing from a combination of Power query, DAX in Power Pivot and CUBE functions in excel?

Thank you

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Answer 1

Rin-L 10,250 Microsoft External Staff Moderator

Hi @P Ng,

Thank you for posting your question in the Microsoft Q&A forum, and I'm truly sorry for the inconvenience you're experiencing.

To better understand your situation, may I kindly ask which version of Excel you’re currently using? (You can check this by going to File > Account > About Excel.)

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Also, could you please confirm whether you're using a business account (provided by your company or school)?

Please understand that our initial response may not always resolve the issue immediately. However, with your help and more detailed information, we can work together to identify the root cause and find a suitable solution.

If you have any updates or additional details, feel free to leave a comment under this post. I’ll be more than happy to assist you further.

If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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PNg-5441 45 Reputation points

2025-09-15T05:02:08.6966667+00:00

Hi,

Thank you for your response. Here is the version of Excel I am using
Rin-L 10,250 Reputation points Microsoft External Staff Moderator

2025-09-15T07:10:05.1766667+00:00

Hi @P Ng,

Thank you so much for your reply.

Based on my research, the error message "Query optimizer generated too many subcubes in the query plan" has been reported by multiple users following the August 2025 update to Microsoft 365 Apps (Version 2508), which matches the version of Excel you're currently using. You can find similar cases discussed here: Power Query Failure After August 2025 Update - Microsoft Q&A

This issue is tied to the Analysis Services engine, where the query optimizer hits a built-in limit on the number of sub-cubes (sub-queries) generated for complex data models or PivotTables. According to Microsoft documentation and support responses, this behavior is by design, intended to prevent excessive resource consumption from overly complex queries. However, it seems the recent update has made this limit more stringent, which is why it may now affect models that previously worked fine.

This could indeed be intentional to encourage simpler, more efficient report models, as the error often stems from factors like numerous calculated measures, extensive hierarchies, or enabled grand totals/subtotals that inflate sub-cube counts.

I completely understand how disruptive this can be, especially when your files have been working reliably for months. However, as a forum moderator, I hope you can understand that I don’t have the ability to modify or escalate product issues directly, I strongly encourage you to submit feedback via the Excel · Community. To save you time, I’ve also found a few existing feedback threads related to this issue. You can support them by voting to help increase visibility:

Update 2508 fails powerpivot queries · Community

Excel Error "Query optmizer generated too many subcubes in the query plan." · Community

Excel Error "Query optmizer generated too many subcubes in the query plan." · Community

If my response has helped you better understand the situation and guided you toward a possible next step, please consider marking it as the “Accepted answer.”

This will pin the post to the top, making it easier for others in the community who may be experiencing the same issue to find our thread and join in by voting or sharing their insights.

Thank you again for your understanding and contribution!
PNg-5441 45 Reputation points

2025-09-15T08:01:38.71+00:00

I am currently using a business account with a Microsoft E3 subscription provided by my company.

I also recognize a significant reduce of performance of Power query, especially in refreshing power query loaded to table
Rin-L 10,250 Reputation points Microsoft External Staff Moderator

2025-09-15T08:24:06.39+00:00

Hi @P Ng,

Thank you again for sharing your thoughtful and practical feedback. I truly understand that you're feeling unsatisfied with your experience, and I sincerely empathize with the frustration this may have caused.

That’s exactly why, within the scope of my support here, I’ve encouraged you to share your feedback directly with the product development team through the official portal. I’m really sorry that I don’t have the authority to submit feedback on your behalf, but your voice is incredibly valuable, and submitting it yourself ensures it reaches the right team for consideration.

I also hope you’ll consider helping bring more visibility to this thread by marking the answer as “Accepted answer”. This will pin the post to the top, making it easier for others in the community who may be facing similar issues to find it, join the conversation, and vote to raise awareness.

Thank you again for your understanding and for being proactive in helping improve the experience!
PNg-5441 45 Reputation points

2025-09-16T06:23:09.68+00:00

Thank you Rin-L. I appreciate your support and time you spend to help me explain the issue.
Rin-L 10,250 Reputation points Microsoft External Staff Moderator

2025-09-16T07:33:16.71+00:00

Hi @P Ng,

Thank you so much for always responding to me with kindness. If you have any other questions, please don’t hesitate to post your question on our forum. I truly hope to have the opportunity to assist you again in the future.

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Power Pivot Data Model refresh goes error after recent Window update on 10-Sep

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