Error when connecting with Azure Blob Storage container

Hi MattMcMillin_71 

1) What this Error actually means

> Malformed web response means Power BI called the Blob REST API, but the response it received was not what Power BI expected

This usually happens due to

* Authentication/token changes

* TLS / security enforcement changes

* Storage account configuration changes

* Container-level access changes

* API throttling or partial outage

2) Most common causes

>Access level changed on the Container

If the container was:

* Public → Private

* Or access policy modified

Power BI can no longer list files.

Check in Azure Portal

* Storage Account → Containers

* Verify Public access level

* If using SAS → check expiry

This is the cause in long-running setups.

>SAS Token Expired

If your connection uses a SAS token, they often

* Expire after 6–12 months

* Are silently rotated by security teams

Symptoms

* Worked fine historically

* Suddenly fails without model changes

Fix

* Generate a new SAS token

* Update Power BI connection

* Republish dataset

> TLS / Security Policy Update

Microsoft recently enforced stricter TLS and API behavior.

If

* Storage account enforces HTTPS-only

* Older Power BI Desktop or gateway is used

Actions

* Update Power BI Desktop

* Update On-Premises Data Gateway

This explains malformed response from a valid endpoint.

>Blob Endpoint now redirecting

Power BI does not like redirects in Blob REST calls.

Example

* Old endpoint → redirected to new region / firewall rule

* Private endpoint introduced

Check

* Networking → Firewalls & virtual networks

* Private endpoint enabled?

* IP restrictions changed?

>Temporary Azure Blob Service Issue

Less common, but possible.

Check

* Azure Service Health

* Any incident for Blob Storage / REST API

3) Quick diagnostics you can do now

Test in Power BI Desktop

1. Open Transform Data

2. Click Refresh Preview

3. If it fails → authentication issue

4. If it loads but service refresh fails → gateway/network issue

Clear & Re-enter Credentials

In Power BI Desktop

* File → Options → Data Source Settings

* Find Azure Blob

* Clear Permissions

* Reconnect

This fixes token corruption issues

 Try Connecting via Folder instead of Container

If you are using

Azure Blob Storage

Azure Data Lake Storage Gen2

(or vice versa)

Some tenants enforce Gen2 behavior now.

4) If you need an emergency workaround

If refresh is business-critical and engineers are unavailable:

Option A Download file locally (Temporary)

* Download blob file manually

* Point Power BI to local copy

* Keep dashboard alive temporarily

Option B Use HTTPS URL + Web Connector (Short-term)

```text

https://<account>.blob.core.windows.net/<container>/<file>

Not ideal, but works for emergencies

A “malformed web response” from Azure Blob usually indicates an authentication, access policy, or security configuration change rather

than a Power BI issue, especially when the solution has worked historically.

Please give heads-up if this is helpful other let us know the issue. Thank you!