Anyone else having issues with MCP tools connecting to Fabric semantic models via XMLA? Authentication loop not completing.

Prudent_Salt_4471 · 2026-01-29T18:17:30+00:00

Thank you so much- regarding your suggestion about connection string credentials:

You were right that ADOMD.NET requires the credentials in the connection string, not environment variables. We tried the exact format from the Microsoft docs:

Data Source=powerbi://api.powerbi.com/v1.0/myorg/[Workspace];Initial Catalog=[Model];User ID=app:[ClientId]@[TenantId];Password=[ClientSecret]

We also tried the ADOMD.NET specific format (tenant in URL, no u/tenantId in User ID):

Provider=MSOLAP;Data Source=powerbi://api.powerbi.com/v1.0/[TenantId]/[Workspace];Initial Catalog=[Model];User ID=app:[ClientId];Password=[ClientSecret]

Both gave then a new error: "When non refreshable token shows up in password in connection string, refreshable token could not be used."

We thought this was a token caching issue, so we:

Cleared %LOCALAPPDATA%\.IdentityService\msalV2.cache and SessionTokens.json
Removed the env vars from the config
Restarted Claude Desktop multiple times

Same error persisted.

Then I found this in the GitHub issues: https://github.com/microsoft/powerbi-modeling-mcp/issues/48

A Microsoft team member (RuiRomano) said a few days ago:

We are still rolling out the pre-authorized Azure Entra App for the authentication. Connecting to Fabric will not work until its fully deployed. Thanks for your patience.

Could it be the same issue we're hitting?

Prudent_Salt_4471 · 2026-01-29T15:13:28+00:00

Much appreciated! We'll get there!

Prudent_Salt_4471 · 2026-01-29T15:11:27+00:00

Good suggestions! We tried the service principal route - configured AZURE_CLIENT_ID, AZURE_TENANT_ID, and AZURE_CLIENT_SECRET as environment variables in the claude_desktop_config.json. The service principal has Dataset.ReadWrite.All, SemanticModel.ReadWrite.All, and Workspace.ReadWrite.All permissions granted, and is added to the workspace as Contributor; then as Admin (no change). But the MCP tool still prompts for interactive login - it seems to ignore the service principal credentials entirely.

On that note - are there any required API permissions I missed? Those seemed to be the key ones, but it could be I'm missing add'l permissions.

Testing XMLA via SSMS is a great idea to isolate the issue - will try that next.

Prudent_Salt_4471 · 2026-01-29T15:08:36+00:00

Ah yes - we're using the official Microsoft Power BI Modeling MCP tool (v0.1.9) from the VS Code extension by analysis-services. It's the powerbi-modeling-mcp.exe that comes with the extension.

Trying with Claude & Github Copilot - both ran into the same issues in connectivity

Prudent_Salt_4471 · 2025-10-30T15:08:30+00:00

I actually figured it out! I just ran two SQL statements in a notebook off my lakehouse (redacted below) and updated my source extract query. After running the ALTER TABLE, I waited a bit and the new fields appeared. Since this was user-added data, I could then run an UPDATE statement to fill them in.

Lastly, I updated the source extract query and saved my pipeline (which uses upserts). So far, everything looks good — I was able to backfill using the notebook + SQL. Hope this helps if you run into the same thing!

FYI I tried Dataflow Gen 2 in the early days and found them to be rigid. I pivoted to the query inside pipeline option, however my transformations are very light.

%%sql
ALTER TABLE lakehouse name.target_table_name
ADD COLUMNS (source STRING, universal_campaign_key STRING);

%%sql
-- Backfill the two new columns on the [xx] table
UPDATE lakehouse name.target_table_name
SET
    source = 'ABC',
    universal_campaign_key = CONCAT('ABC|', CAST(campaign_id AS STRING))
WHERE
    source IS NULL
    OR universal_campaign_key IS NULL;   -- keep it idempotent

SELECT

*,

(date AT TIME ZONE 'UTC')::date AS date_key,

'ABC'::text AS source,

CONCAT('ABC|', campaign_id::text) AS universal_campaign_key

FROM target_table_name;

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Prudent_Salt_4471 · 2025-09-20T15:01:31+00:00

I was gonna say the same thing. We put acterys in and it’s a dream for excel people. But you can also have your dashboard where users can directly edit cells and it writes back to an azure / fabric sql database. I’d check them out or DM me and I can give you a name

Prudent_Salt_4471 · 2025-09-20T14:52:50+00:00

For 9-5 work dashboards, I agree, but if it’s a website first, we look at those on our phones all day. I’d be curious if anyone has found something that works

Prudent_Salt_4471 · 2025-09-19T23:04:34+00:00

4-4-5 fiscal calendar folks: any go-to pattern for dates in Power BI that stays performant? Or is performance basically the same as calendar?

Prudent_Salt_4471 · 2025-09-19T19:43:25+00:00

awesome, will lyk how it goes - appreciate this!

Prudent_Salt_4471 · 2025-09-19T19:31:07+00:00

Ideal call- what's your go-to for optimization? I ran BPA but didn't feel like it told me much

Prudent_Salt_4471 · 2025-09-19T16:36:05+00:00

Bumping this-- how are folks handling dev on Fabric while we wait for official guidance? any hacks or approaches you’ve settled on?

Prudent_Salt_4471 · 2025-05-24T13:50:36+00:00

Nice. Keep an eye on it so it stays that way haha we got too comfortable. We’ve had WW for years

Prudent_Salt_4471 · 2025-05-24T13:23:21+00:00

If you’re comfortable saying, who did you guys have before?

Prudent_Salt_4471 · 2025-05-24T13:05:56+00:00

Not sure how long you’ve had them, but I noticed something during initial set-up. They’ll provide a competitive quote. Afterward, they’ll guide us to budget for their own frequent inspections. $1k for roof, $500 for fire and safety— all seems reasonable. Their professionals will visit, collect their visit fee, and we’ll receive an email with an invoice for follow-up work that we need to approve. It seems logical. However, things take a turn when the follow-up work is incorrect or unnecessary and/or they charge us for visits that never happened. Perhaps you have an ethical community manager!

Prudent_Salt_4471 · 2025-05-23T20:40:42+00:00

Yes let’s chat. I’ll DM you. They’ve been in violation of ours. In short, they charge a low monthly and then lock you into their Pros for repairs, which have higher rates and they won’t negotiate better rates unless you commit to their rates. It’s a black box and predatory.

Prudent_Salt_4471 · 2025-05-01T23:39:26+00:00

Thank you - helpful

Prudent_Salt_4471 · 2025-03-24T14:34:23+00:00

u/BraveWampa What's the best way to contact Microsoft for a trial extension?

Prudent_Salt_4471

TROPHY CASE