Unable to connect pipeline to Warehouse

[DShallcross]

Hello, 

I am unable to connect to my Fabric warehouse using a pipeline. This was working and seems to have started overnight. We haven't made any changes to the pipeline or the warehouse. I created the connection in the pipeline following this in the documentation Set up your Data Warehouse connection - Microsoft Fabric | Microsoft Learn There is no error message, when trying to preview data in a lookup activity it just times out. I cannot see a list of tables either in the dropdown as the connection times out. I can run manual queries in the warehouse in SQL.  The connection has been running successfully for months then seemingly stopped working overnight. I can access our external database via a pipeline and that copies data fine into our lakehouse. I just can't seem to query data from the Fabric warehouse using the pipeline. We do not encrypt our data warehouse or use CMK. Any help? Below is image of what I can see. Any help is appreciated

[NandanHegde · Accepted solution]

Can you confirm in which region your capacity is?
There are some downtime time out issues happening in uk south region :

https://statusgator.com/services/microsoft-fabric

[DShallcross]

Yep we are UK South - seems to be back online now as our pipelines are working again. Dissapointing from Microsoft as there was no outage mentioned on their website.

[Lodha_Jaydeep]

HI @DShallcross,

Thank you for the detailed description! Based on the **WebRequestTimeout** error and the fact that this stopped working overnight without any changes on your end, here are the most likely causes and steps to resolve it:

**1. Re-authenticate the Connection**
The saved connection token may have expired silently. Try:
- Go to **Manage connections and gateways** in Fabric
- Find your Warehouse connection and click **Edit**
- Re-enter credentials and save
- Then re-test the Lookup activity

**2. Check Capacity Status**
Your Fabric capacity may have been paused or throttled:
- Go to **Azure Portal → Fabric Capacity**
- Ensure the capacity is **Active** and not paused

**3. Delete and Recreate the Connection**
If re-authenticating doesn't work:
- Remove the existing connection from the Lookup activity
- Create a brand new connection to the Fabric Warehouse
- Re-run the pipeline

**4. Increase Timeout Settings**
In the Lookup activity **Settings** tab, try increasing the **Timeout** value (default is usually 00:10:00) to a higher value like 00:30:00.

**5. Raise a Microsoft Support Ticket**
Since this was working for months and stopped overnight with no changes, and given the Activity ID in your error ('3e2f1621-670d-483a-953e-f21823ab8df4'), it's worth raising a **Microsoft Fabric support ticket** with this Activity ID so they can investigate on their end.

Hope one of these helps resolve the issue! Let us know what you find. Consider this as accepted solution if work for you!

[Tamanchu]

Hi @DShallcross ,

When a Warehouse pipeline connection that worked for months suddenly times out without error, the most common causes are:

1. Expired OAuth connection (most likely)
Pipeline connections to Fabric Warehouse use OAuth tokens that can expire or become stale. Even if nothing changed on your end, the token behind the connection may have silently expired.
→ Go to your pipeline → click the Warehouse connection → select Edit connection → re-authenticate (sign in again). Then retry.

2. Check for an active Fabric service incident
If the issue appeared overnight with no changes, check the Microsoft service health dashboard:
→ admin.fabric.microsoft.com → Health → Service health or the Microsoft 365 admin center under Service Health. Look for any Fabric Data Factory or Warehouse incidents.

3. Capacity throttling
If your Fabric capacity was under heavy load overnight (scheduled jobs, refreshes), it may have been throttled pipeline connectors are often the first to timeout in this case.
→ Check the Fabric Capacity Metrics app in your workspace for any spikes around the time it stopped working.

4. Increase the activity timeout
If the warehouse SQL endpoint is in a cold state, the default timeout may not be enough.
→ In the Lookup activity settings → increase the Timeout value (e.g., from 00:10:00 to 00:30:00) and retry.

Since manual queries work fine in the Warehouse directly, the warehouse itself is healthy the issue is in the pipeline-to-warehouse connection layer. Start with re-authenticating the connection.

Hope this solution can help you !