Power BI shows old years from REST API, while Postman & a fresh PBIX show correct data

[rouzbehrasai]

Hi all,
I’m stuck with an odd caching issue when pulling JSON from a REST API via Web.Contents.

Context

• Source: http://thestaff.co.in:8000/api/v1/statistics/vgs/students
• Auth: Bearer JWT in header
• Desktop version: (add your exact PBID version)
• Privacy level: Organizational (tried others as well)
• Endpoint returns a JSON object with fields like: data (list), total_records, page, page_size, and a boolean cached.
  In Power BI I frequently see cached = TRUE in the parsed JSON.

Symptoms

• In my existing PBIX, after refresh I still get years 2018 and 2019.
• The same M query in a fresh new PBIX returns correct data (no 2018/2019).
• Postman also returns correct data (no 2018/2019).
• The API response preview inside Power Query shows cached = TRUE when the old years appear.

Minimal M (sanitized)

let

    BaseUrl = "http://thestaff.co.in:8000",

    Path = "api/v1/statistics/vgs/students",

    Source = Web.Contents(

        BaseUrl,

        [

            RelativePath = Path,

            Query = [

                page = "1",

                page_size = "-1",

                sort_order = "asc"

            ],

            Headers = [

                Accept = "application/json",

                Authorization = "Bearer " & pToken   // pToken is a text parameter (JWT only)

            ]

        ]

    ),

    Json = Json.Document(Source)

in

    Json

What I’ve already tried (no change):

1. Cleared Data Source Settings for the domain (Global & Current File) and re-authenticated as Anonymous.
2. Cleared Power BI cache (File → Options → Data Load → Clear cache) and disabled background previews.
3. Closed/reopened PBID and refreshed.
4. Verified there are no duplicate/staging tables being loaded; checked Query Dependencies to ensure nothing is appending/merging old sources.
5. Temporarily inactivated relationships and tested visuals that use only the API table.
6. Confirmed no Incremental Refresh partitions or calculated snapshot tables.
7. Added cache-busting:
• Headers:
• #"Cache-Control" = "no-cache, no-store",
• Pragma = "no-cache"
• Query param: _ts = DateTime.ToText(DateTimeZone.UtcNow, "yyyyMMddHHmmss")
  Still seeing cached = TRUE in the JSON in the old PBIX.
8. Replaced the query by creating a new one with the working M (from the fresh PBIX), then renamed/swap-in. The issue sometimes persists until I fully rebuild the PBIX.

Observations

• When the issue occurs, the JSON root I see in Power Query includes cached = TRUE.
• Postman, using identical params/headers, returns the expected dataset (no 2018/2019).
• A brand-new PBIX with the same M also returns the correct dataset.

Questions for experts

1. Is there any Power Query/Power BI Desktop caching layer (beyond the standard cache I already cleared) that could cause a persisted, request-level cache for Web.Contents?
2. Are there known behaviors where request keying for Web.Contents could reuse a cached response even with different Query params/headers?
3. Any recommended way to force a cache miss from Power BI (e.g., special options, Binary.Buffer placement, or using Web.Contents’s Query vs RelativePath nuances) to guarantee a fresh call?
4. Could Privacy levels, Fast Combine, or Preview caching still interfere even after being cleared?
5. Is there any diagnostic approach (Query Diagnostics / Fiddler) you recommend to confirm what HTTP request PBID actually sends and whether the server is truly serving a cached artifact?

Goal
Make Power BI always pull fresh data from the API (matching Postman and the fresh PBIX), or at least reliably bypass any server or PBID cache when needed.

Happy to share additional sanitized logs or a tiny PBIX if helpful. Thanks!

[parry2k]

@rouzbehrasai Quick question, is it in PQ preview that you are seeing the cache data, or when you actually load the data in the model, it still shows the old data

[rouzbehrasai]

Thank for reply.

Both.

In the old PBIX, I see the stale years already in Power Query preview (the parsed JSON root shows cached = TRUE). If I then load to the model, the table/visuals also include 2018/2019. And other updated data in the database is not shown correct in the report. 

In a brand-new PBIX with the same M and token, preview and model are correct (no 2018/2019), and the cached flag is absent/false. The other updated data is also visible and updated in this report. 

[v-hjannapu]

Hi @rouzbehrasai ,

Thank you  for reaching out to the Microsoft fabric community forum.

 It looks like the old PBIX file is still holding some old cached data from the API. Even after clearing the normal cache, sometimes Power BI keeps a local cache for Web.Contents when the same URL and settings are used.

You can try adding a random query parameter in your API call with a random number, so that Power BI treats every refresh as a new request. After that, close Power BI and delete the files from folder .

Also, you can check by setting the privacy level to Ignore once for testing. If it still shows old data, you can use Fiddler or Query Diagnostics to see if Power BI is actually sending a new API request.

Since the new PBIX is showing the correct data, it confirms the API is fine. The issue is with cache stored in the old file. If the above steps don’t help, rebuilding the query in a new PBIX might be the best option.

Hope this helps. Let me know if the data updates properly after trying these steps.
Regards,
Community Support Team.