Purview REST API: classification has instance count of 0 but I cannot delete it

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Purview REST API: classification has instance count of 0 but I cannot delete it

Francesco Castellani 100

In the UI, I'm trying to delete a classification that has no assets associated with it.

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But I cannot:

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What are these references if they're not assets using this particular classification?

If I try to do this using Postman or the REST API, I get the following. How can I solve this?

409 Client Error: Conflict for url: https://<catalogue-name>.purview.azure.com/catalog/api/atlas/v2/types/typedefs

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Answer 1

Pilladi Padma Sai Manisha 7,310 Microsoft External Staff Moderator

Hi Francesco Castellani
Thank you for reaching out to Microsoft Q&A!, regarding the custom classification deletion issue in Microsoft Purview. The "has references" error despite showing "0 instances" typically indicates hidden dependencies such as classification rules, typedef references, or internal metadata links that must be cleaned up first.

Step-by-Step Resolution

Remove Applied Classifications from Assets

Even if UI shows 0, verify and clear any lingering tags using GET https://{catalog}.purview.azure.com/datamap/api/atlas/v2/search/basic?typeName=*&query=Application_documents_UAT. If results appear, use bulk classification removal via POST https://{catalog}.purview.azure.com/datamap/api/atlas/v2/entity/bulk/classification with body {"entities": [{"typeName": "asset_type", "guid": "entity_guid"}], "classificationNames": ["Application_documents_UAT"]}.

Delete Classification Rules:

Navigate to Data Map > Classification rules > Custom tab in Purview Studio, filter for rules referencing Application_documents_UAT, select, and delete. API alternative: GET https://{catalog}.purview.azure.com/datamap/api/atlas/v2/entity/type/ClassificationRule then DELETE /atlas/v2/entity/guid/{rule-guid} for matches.

Inspect and Delete Typedef:

Check dependencies with GET https://{catalog}.purview.azure.com/datamap/api/atlas/v2/types/typedef/name/Application_documents_UAT. Once clean, delete using DELETE https://{catalog}.purview.azure.com/datamap/api/atlas/v2/types/typedefs with body {"classificationDefs": [{"name": "Application_documents_UAT"}], "enumDefs": [], "structDefs": [], "entityDefs": [], "relationshipDefs": []}.

If Deletion Still Fails

The 409 error may require backend cleanup of internal references. Please collect full API response/error details, share your Purview account name and classification GUID, and open a support ticket via Azure Portal > Purview > New support request.

Key References:

Custom classifications management Purview Data Plane Type APIs Atlas 2.2 typedef operations

Let us know your results or if you need assistance with API authentication.

Francesco Castellani 100 Reputation points

2026-02-27T18:41:01.4+00:00
Hi, thanks for your answer, but step 1, the first API call you suggest may not be correct, because I send: GET https://<catalogue-name>.purview.azure.com/datamap/api/atlas/v2/search/basic?typeName=*&query=Application documents_uat and I get the below message, but the classification name is not spelled incorrectly.

{ "requestId": "c61869ee-8b8b-4bab-b093-e32b4e7bff30", "errorCode": "RequestInvalid", "errorMessage": "Request is not recognized. Please verify the HTTP method, header or URL" }
Pilladi Padma Sai Manisha 7,310 Reputation points Microsoft External Staff Moderator

2026-03-02T18:16:29.6866667+00:00
Hi Francesco Castellani
Thank you for testing that and for sharing the error details.

You are correct to question that first call – the URL I suggested was not using the current, supported search endpoint and format, which is why you are seeing:

"errorCode": "RequestInvalid", "errorMessage": "Request is not recognized. Please verify the HTTP method, header or URL".

In the latest Purview Data Map APIs, asset search is done via the Discovery – Query endpoint, not the legacy atlas/v2/search/basic. You can instead use:

POST https://<catalogue-name>.purview.azure.com/datamap/api/search/query?api-version=2023-09-01

with a JSON body like:

json { "keywords": "Application_documents_UAT", "limit": 50, "filter": { "and": [ { "classification": "Application_documents_UAT" } ] } }

This will return any assets that still have that classification applied, if there are any.

So to clarify step 1 of my previous answer:

The GET .../datamap/api/atlas/v2/search/basic?... URL was incorrect for the current API version and can safely be ignored.

Please use the POST .../datamap/api/search/query?api-version=2023-09-01 endpoint with a body like the one above to check for remaining uses of your classification instead.

Once you confirm there are no results from the Discovery API, you can continue with the remaining cleanup steps (classification rules, then typedef delete).
Pilladi Padma Sai Manisha 7,310 Reputation points Microsoft External Staff Moderator

2026-03-03T21:23:02.73+00:00

Hi **Francesco Castellani
**Following up to see if the below answer was helpful. If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

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Purview REST API: classification has instance count of 0 but I cannot delete it

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