topic Data Agent fails to query Ontology in IQ

Data Agent fails to query Ontology

sdinev — Wed, 22 Apr 2026 14:33:51 GMT

Hello,
I’m experiencing an error when using the Data Agent in Microsoft Fabric to query my Ontology.
Even when I ask very simple questions, the Data Agent fails every time with the following error:

Failed to execute step (RAID: "GUID"). Error: Failed to generate NL2Ontology query with error "{"code":"InternalError","subCode":0,"message":"An internal error occurred.","timeStamp":"2026-04-20T13:00:42.7677176Z","httpStatusCode":500,"hresult":-2147467259,"details":[{"code":"RootActivityId","message":"GUID"},{"code":"Param1","message":"Failed to translate NL query to ontology query."}]}"

This was working correctly until last week, but for the past four days it has consistently failed with the error above, without any changes on my side.
The Data Agent works perfectly when querying:
a Lakehouse (NL2SQL), and
a Semantic Model (NL2DAX).
The issue occurs only when the Ontology is used as the data source.

Also I have "Support GROUP BY in GQL" inside the data agent's instructions.

Could someone please help me understand what might have changed recently or how to troubleshoot this issue?
Thank you in advance.

Re: Data Agent fails to query Ontology

arabalca — Fri, 24 Apr 2026 06:05:31 GMT

Hi sdinev ,

Does the error persist?

Based on the error you're describing, the issue seems to be in the NL2Ontology translation layer on the Fabric IQ backend, not in your ontology or your data. The fact that NL2SQL and NL2DAX work perfectly confirms this.

Try these steps in order and let us know if any of them resolves it:

Verify that the agent instruction text is exactly Support group by in GQL
in English, with no variations, quotes, or extra characters. Reference: https://learn.microsoft.com/en-us/fabric/iq/ontology/tutorial-4-create-data-agent#provide-agent-instructions
Check the data bindings health in the ontology preview experience: entity types should load, relationships should be visible, and the Graph should not be empty. A broken binding can cause NL2Ontology to fail when trying to introspect the schema, even if the error message doesn't make that obvious. Reference: https://learn.microsoft.com/en-us/fabric/iq/ontology/resources-troubleshooting
Recreate the Data Agent from scratch pointing to the same ontology. The agent can end up in a corrupted state after a silent service-side update.
Confirm that all required tenant settings are still enabled, including Data agent item types . Fabric deployments can occasionally reset these. Reference: https://learn.microsoft.com/en-us/fabric/iq/ontology/overview-tenant-settings
Open a support ticket at https://support.fabric.microsoft.com including the RootActivityId GUID from the error. That identifier allows Microsoft to correlate with the internal NL2Ontology pipeline logs.

If my comment helped solve your question, it would be great if you could like the comment and mark it as the accepted solution. It helps others with the same issue and also motivates me to keep contributing.

Thanks a lot, I really appreciate it.

Re: Data Agent fails to query Ontology

AngelKostadinov — Fri, 24 Apr 2026 09:40:56 GMT

Same story here, starting from this week, our Data agent has stopped working, throwing the same error!

Re: Data Agent fails to query Ontology

sdinev — Fri, 24 Apr 2026 09:46:53 GMT

Hello,

I followed the troubleshooting steps from Microsoft Learn.

I verified that the Data Agent instruction text is exactly: Support group by in GQL
(with no variations or extra characters).

I checked the ontology preview experience and the data bindings health: entity types load correctly, relationships are visible, and the Graph is not empty.

I recreated the Data Agent from scratch and pointed it to the same ontology, but the issue still persists. Recreating the agent is recommended in the tutorial when troubleshooting initialization or agent behavior.

However, I am blocked on step 4: I cannot find the tenant setting “Users can create and share Data agent item types (preview)” anywhere in the Fabric Admin portal tenant settings. According to the documentation, this setting is required in order to create or use a Fabric Data Agent with an ontology source, but it does not appear in our tenant UI.

Do you think these attached screenshots have anything related to the problem ?

On the first image there is no Ontology or Graph mentioned regarding the Data Agent GA.
On the second image Microsoft says that NL2GQL is planned.

Re: Data Agent fails to query Ontology

apturlov — Tue, 26 May 2026 17:09:22 GMT

sdinev If you can create a Data agent in a workspace which requires an F-SKU commercial Fabric capacity, and can add an existing Ontology to this agent as a data source, then your Fabric tenant settings are correct.

I've been struggling with the same error for many weeks until I noticed that if an Ontology and a Data Agent are in the same workspace the error suddently disappears and all works.

The fact is that Ontology is in Preview and changes dramatically very often. I strongly recommend aginst any productionized usage of Ontology as the data source for the time being until it reaches GA. There are a lot of kinks in Ontology that have to be sorted out before it happens.

Considering that any Ontology is based on other Fabric data sources - Lakehouses and Eventhouses, I suggest to use the Ontology data sources directly in your Data agents instead and provide good instructions for both Agent logic and data sources themselves to compensate for not using an Ontology. You cannot directly replace Ontology relationships in Graph with anything else especially when it comes to cross-storage relationships like KQL table and Lakehouse table so you need to cover this with the instructions and sample queries. Using a Semantic model for your Data agent may help but only for Lakehouse data as you cannot integrate KQL tables into a Semantic model yet.

Hope this helps to prioritize your efforts in delivering a working Data agent experience instead of fighting internal issues of the Ontology workload. I am a big fan of Ontology but after experimenting for many weeks and being in direct contact with Microsoft team I decided that it's still too early to rely on Ontology as a data source for Data Agents.

Re: Data Agent fails to query Ontology

yoursam — Fri, 26 Jun 2026 22:24:54 GMT

I have created a Fabric Data agent which is using source as Fabric IQ Ontology, however when I am trying to query data , getting some technicall issue as below ... Also, I have added this in Agent Instrctions to "Support group by in GQL"

The system could not process the query as phrased, so I was unable to retrieve campaign delivery performance data including delivery counts and bounce rates. This issue is typically due to technical limitations in interpreting the query.
You can try rephrasing your request, specifying the time range, specific campaigns, or clarifying the format you want. If you have another way you'd like this data queried or displayed, please let me know!
The error details shown below the message read:
Failed to execute step (RAID: f6c22cfe-2672-42e4-add5-2f6238667664). Error: Failed to generate NL2Ontology query with error
{"code":"BadRequest","subCode":0,"message":"The request is invalid. The natural language query could not be processed. Please rephrase your query and try again.","timestamp":"2026-06-15T23:41:02.8454246Z","httpStatusCode":400,...}
From the screenshot, the original query appears to be:
"Show campaign delivery performance including delivery counts and bounce rates for each campaign."
This suggests the semantic model could not translate the natural language request into a valid ontology query. You may have better success by using a more specific query such as:
Show delivery count, delivered count, bounced count, and bounce rate by campaign for the last 30 days.
List all campaigns with emails sent, delivered, bounced, and bounce percentage.
Campaign performance report grouped by campaign name showing delivery and bounce metrics.
For each campaign, show Sent, Delivered, Bounced, Delivery Rate, and Bounce Rate.
If you're using a Power BI semantic model/Copilot, I can also help rewrite the prompt based on your dataset schema.

Re: Data Agent fails to query Ontology

Billybob0604 — Fri, 11 Sep 2026 06:51:02 GMT

Adding our findings here, since we hit the exact same pattern but were able to rule out the fixes suggested earlier in this thread.

Setup: Fabric Data Agent with an Ontology (generated from a Power BI semantic model) as data source, F4 capacity.

Symptom: identical to what's described above — structural/metadata questions work fine ("What is a ........?", "What properties does ....... have?", "What relationships does ......have?"), but any question requiring instance-level data fails consistently with:

"Unable to generate code: The request is invalid. The natural language query could not be processed. Please rephrase your query and try again.

What we ruled out, in case it helps others:

Same workspace: our Ontology and Data Agent are already in the same workspace — this did not resolve it for us, unlike what was reported earlier in this thread.
Graph/data binding health: confirmed healthy. A direct GQL query against the Ontology (bypassing the Agent entirely) returns correct, aggregated results, e.g. SUM(k.Bedrag) returned the correct total. So the underlying data, relationships, and even aggregation work fine at the Ontology level itself.
"Support group by in GQL" instruction: added exactly as documented, no effect.
Runtime (Standard vs Preview): tested both, identical failure in both.
Tenant settings (Copilot/Azure OpenAI, Ontology preview): confirmed enabled for our security group.

Conclusion on our end: since GQL queries succeed directly against the Ontology but fail via the Agent's natural-language interface, this points specifically to the NL2Ontology translation layer inside the Data Agent tool (analyze_ontology) as the failure point.

I m opening an official support ticket with the RAID so Microsoft can correlate with internal pipeline logs. Will report back if we learn anything.

Cheers
William