The answer is that the enterprise signing certificate is not trusted on the device. This error code 0x87D13B9F occurs because iOS requires the enterprise certificate used to sign the LOB app to be installed and trusted in the device’s trusted root store; without that trust, the operating system blocks the installation as a security measure. On the Microsoft 365 Endpoint Administrator MD-102 exam, this scenario tests your understanding of iOS certificate deployment via Intune, often appearing as a trap where candidates mistakenly blame the app package or provisioning profile instead of the missing root certificate. A common memory tip is to think of the error as a “trust gap”—the device simply doesn’t recognize the signer, so you must push the enterprise root certificate using a trusted certificate profile before deploying the app.
MD-102 Prepare infrastructure for devices Practice Question
This MD-102 practice question tests your understanding of prepare infrastructure for devices. 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 manage devices with Microsoft Intune. You need to deploy a line-of-business (LOB) app to iOS devices. The app is signed with an enterprise certificate. Some devices report installation failure with error code 0x87D13B9F. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The enterprise signing certificate is not trusted on the device.
Error code 0x87D13B9F in Microsoft Intune typically indicates a signing certificate trust issue. Since the app is signed with an enterprise certificate, the device must have that certificate installed and trusted in its trusted root store. If the certificate is not trusted, iOS will reject the installation, producing this specific error.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The app package is not signed.
Why it's wrong here
The question states the app is signed; if it weren't, the error would be different.
✗
The app is not available in the Apple App Store.
Why it's wrong here
LOB apps are deployed directly, not through the App Store.
✓
The enterprise signing certificate is not trusted on the device.
Why this is correct
Error 0x87D13B9F indicates that the app's signing certificate is not trusted, often because the certificate profile is missing.
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 device does not have enough storage space.
Why it's wrong here
Storage errors have different codes, e.g., 0x80070070.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may confuse a signing error (missing certificate trust) with a packaging error (unsigned app), but the error code 0x87D13B9F specifically points to trust, not signature absence.
Detailed technical explanation
How to think about this question
Enterprise-signed iOS apps rely on a provisioning profile and a signing certificate that must be trusted by the device. Intune deploys the app via the Company Portal, which uses the Apple Device Enrollment Program (DEP) or manual certificate installation to establish trust. If the enterprise certificate's root or intermediate CA is missing from the device's trust store, iOS will fail the installation with error 0x87D13B9F, which maps to 'ApplicationInstallFailure' in Intune's diagnostic logs.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this MD-102 question in full detail.
Prepare infrastructure for devices — This question tests Prepare infrastructure for devices — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The enterprise signing certificate is not trusted on the device. — Error code 0x87D13B9F in Microsoft Intune typically indicates a signing certificate trust issue. Since the app is signed with an enterprise certificate, the device must have that certificate installed and trusted in its trusted root store. If the certificate is not trusted, iOS will reject the installation, producing this specific error.
What should I do if I get this MD-102 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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