Quick Answer
The answer is a scheduled reboot of the on-premises data gateway at 2:00 AM. This is the most likely cause because a consistent refresh failure at the exact same time every day points directly to a recurring event on the gateway itself, not a transient cloud issue. Enterprise gateways are often configured to reboot during low-activity windows for updates or maintenance, and if that reboot coincides with the refresh schedule, the gateway becomes unavailable, causing the failure. On the PL-300 exam, this scenario tests your ability to distinguish between gateway-side and cloud-side issues—a common trap is assuming the cloud service is at fault, but a perfectly consistent failure at the same time is a dead giveaway for a local scheduled event. Memory tip: think “same time, same gateway crime”—if the failure is clockwork, check the gateway’s maintenance window first.
This PL-300 practice question tests your understanding of deploy and maintain assets. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
You have a Power BI dataset that is refreshed every hour from an on-premises data source using an enterprise gateway. The refresh consistently fails at 2:00 AM. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
The on-premises data gateway is scheduled to reboot at 2:00 AM.
A reboot would cause the gateway to be unavailable.
The refresh is failing due to a transient network error.
Why wrong: Transient errors are not consistent.
The data source is undergoing maintenance in the cloud.
Why wrong: The source is on-premises.
The scheduled refresh time conflicts with another refresh.
Why wrong: Conflicts cause queuing, not consistent failure.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
The on-premises data gateway is scheduled to reboot at 2:00 AM.
The consistent failure at exactly 2:00 AM strongly points to a scheduled event on the on-premises data gateway, such as a reboot or maintenance window. Enterprise gateways can be configured to reboot periodically for updates or health reasons, and if this coincides with the refresh schedule, the gateway will be unavailable, causing the refresh to fail. Transient errors or cloud maintenance would not produce a perfectly consistent daily failure at the same time.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
The on-premises data gateway is scheduled to reboot at 2:00 AM.
Why this is correct
A reboot would cause the gateway to be unavailable.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
The refresh is failing due to a transient network error.
Why it's wrong here
Transient errors are not consistent.
The data source is undergoing maintenance in the cloud.
Why it's wrong here
The source is on-premises.
The scheduled refresh time conflicts with another refresh.
Why it's wrong here
Conflicts cause queuing, not consistent failure.
Common exam traps
Microsoft often tests the concept that consistent, time-specific failures are almost always due to a scheduled event on the gateway or data source, not random network issues or cloud-side problems, which candidates might incorrectly assume due to lack of familiarity with gateway maintenance windows.
Detailed technical explanation
The on-premises data gateway uses a Windows service (PBIEgwService) that can be configured to reboot via scheduled tasks or Windows Update. When the gateway restarts, it loses its connection to the Power BI service, and any refresh attempt during the downtime will fail with an error like 'Unable to connect to the data source' or 'Gateway not reachable'. The gateway's heartbeat mechanism (every 5 minutes) will detect the outage, but the refresh will not retry automatically unless configured with a retry policy.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
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FAQ
Deploy and maintain assets — This question tests Deploy and maintain assets — Read the scenario before looking for a memorised answer..
The correct answer is: The on-premises data gateway is scheduled to reboot at 2:00 AM. — The consistent failure at exactly 2:00 AM strongly points to a scheduled event on the on-premises data gateway, such as a reboot or maintenance window. Enterprise gateways can be configured to reboot periodically for updates or health reasons, and if this coincides with the refresh schedule, the gateway will be unavailable, causing the refresh to fail. Transient errors or cloud maintenance would not produce a perfectly consistent daily failure at the same time.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Same concept, more angles
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. You review the dataset refresh history. The second refresh took 30 minutes and failed. What is the most likely reason for the failure?
easyWhy C: The second refresh took 30 minutes and failed, which strongly indicates the refresh exceeded the default 30-minute timeout limit configured in the on-premises data gateway. When a dataset refresh operation in Power BI runs longer than the gateway's timeout setting, the gateway terminates the connection, causing the refresh to fail. This is a common issue when refreshing large datasets or complex queries through a gateway.
Last reviewed: Jun 30, 2026
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