PL-300 Prepare the data Practice Question
You are connecting to an on-premises Oracle database from Power BI Service. The gateway is installed and configured. However, the scheduled refresh fails with an error indicating that the data source credentials are invalid. Which TWO steps should you take to resolve the issue? (Choose two.)
⚠ Common exam trap
Many candidates assume re-publishing or editing the report in Power BI Desktop will propagate credential changes to the gateway, but Power BI Service stores credentials independently for scheduled refresh, and only updating them in the gateway settings resolves the issue.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Update the data source credentials in the gateway settings in Power BI Service.
The scheduled refresh failure indicates that the stored credentials for the on-premises Oracle data source in Power BI Service are invalid. You must update the data source credentials in the gateway settings under 'Manage gateways' in Power BI Service to provide a valid username and password that the gateway can use to authenticate against the Oracle database. Option C is correct because the gateway machine requires the Oracle client software (e.g., Oracle Data Access Components or ODP.NET) to be installed and configured, and the gateway must have network connectivity to the Oracle server; verifying these ensures the gateway can reach and authenticate with the database.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Re-publish the Power BI report from Power BI Desktop.
Why it's wrong here
Re-publishing the Power BI report from Power BI Desktop only updates the report definition, visuals, and data model in the service; it does not alter or refresh the credentials stored for the on-premises Oracle data source in the gateway configuration. Gateway credentials live in the Power BI Service's data source settings, not within the .pbix file, so this action cannot resolve an authentication or refresh failure caused by expired or incorrect Oracle credentials.
- ✓
Update the data source credentials in the gateway settings in Power BI Service.
Why this is correct
Updating the data source credentials in the gateway settings in Power BI Service is the correct resolution because the service uses those stored credentials every time it refreshes data through the on-premises data gateway. If the Oracle password changed, the account was locked, or the stored credentials simply expired, the refresh fails with authentication errors. Editing the data source in the service, re-entering the username and password, and re-testing the connection re-establishes a valid identity, allowing the refresh to succeed without altering the report or gateway installation.
- ✓
Verify that the gateway machine can connect to the Oracle server and that the Oracle client is installed.
Why this is correct
Verifying that the gateway machine can connect to the Oracle server and that the Oracle client is installed is a valid corrective step because the gateway runs as a separate service on a local machine and enforces its own prerequisites. Without a reachable Oracle listener on the target host and an appropriate Oracle client (such as ODP.NET) installed on that gateway machine, any refresh attempt fails at the network or driver level, even if the credentials are correct. Confirming connectivity and client presence isolates whether the fault lies in the infrastructure rather than the identity, and is a necessary complement to credential updates.
- ✗
Edit the data source settings in Power BI Desktop and republish.
Why it's wrong here
Editing the data source settings in Power BI Desktop and republishing does not affect the gateway's data source configuration because those settings are managed exclusively in the Power BI Service. When a report relies on an on-premises data gateway, the service stores connection details, credentials, and data source mappings independently of the report. Changes made in Desktop are uploaded only as part of the report file, so they cannot update or correct the credentials that the gateway uses during a scheduled or on-demand refresh.
- ✗
Reinstall the on-premises data gateway.
Why it's wrong here
Reinstalling the on-premises data gateway is an unnecessarily disruptive action that requires re-registering the gateway, recreating all data source connections, and reauthorizing every report that depends on it. The symptom described—an inability to refresh an Oracle data source—is almost always due to invalid stored credentials, a prerequisite problem like a missing Oracle client, or a network issue, not a malfunction of the gateway software itself. Reinstallation would not fix credential invalidity and would introduce significant overhead, making it a last-resort measure rather than an appropriate first step.
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