Question 116 of 928

Design and implement build and release pipelines →mediumMultiple ChoiceObjective-mapped

Fixing OIDC Authentication Errors for Azure Storage Static Website Deployments

This AZ-400 practice question tests your understanding of design and implement build and release pipelines. 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.

Your team uses GitHub Actions to build and deploy a static website to Azure Storage. The workflow uses the 'azure/storage-blob-upload' action to deploy to a storage account static website. Recently, deployments started failing with 'Error: Failed to get credentials'. The workflow uses OpenID Connect (OIDC) for authentication. 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.

A
The service principal used for OIDC does not have the 'Storage Blob Data Contributor' role on the storage account.
Role assignment is required for OIDC to access the resource.
B
The storage account firewall is blocking the GitHub Actions IP range.
Why wrong: Firewall would cause connection timeout, not credential error.
C
The OIDC configuration in GitHub is missing the 'client secret' field.
Why wrong: OIDC does not use client secrets.
D
The 'azure/storage-blob-upload' action does not support static websites.
Why wrong: It supports static websites via the 'app-type' input.

Full breakdown with real-world context →

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

✓

The service principal used for OIDC does not have the 'Storage Blob Data Contributor' role on the storage account.

The 'azure/storage-blob-upload' action requires the service principal used for OIDC authentication to have the 'Storage Blob Data Contributor' role on the storage account to upload static website content. Without this role, the action fails to obtain credentials for blob write operations, resulting in the 'Failed to get credentials' 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 service principal used for OIDC does not have the 'Storage Blob Data Contributor' role on the storage account.
Why this is correct
Role assignment is required for OIDC to access the resource.
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 storage account firewall is blocking the GitHub Actions IP range.
Why it's wrong here
Firewall would cause connection timeout, not credential error.
✗
The OIDC configuration in GitHub is missing the 'client secret' field.
Why it's wrong here
OIDC does not use client secrets.
✗
The 'azure/storage-blob-upload' action does not support static websites.
Why it's wrong here
It supports static websites via the 'app-type' input.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse authentication (OIDC token exchange) with authorization (role assignment), assuming a valid OIDC configuration automatically grants access, when in fact the service principal must have the appropriate Azure RBAC role on the target resource.

Detailed technical explanation

How to think about this question

OIDC authentication in GitHub Actions uses a short-lived token from GitHub's OIDC provider, which Azure AD validates to issue an access token for the service principal. The 'Storage Blob Data Contributor' role is required because the action uses the Azure REST API to upload blobs to the $web container; without this role, the token lacks the necessary 'Microsoft.Storage/storageAccounts/blobServices/containers/blobs/write' permission, causing credential acquisition to fail.

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.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this AZ-400 question test?

Design and implement build and release pipelines — This question tests Design and implement build and release pipelines — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The service principal used for OIDC does not have the 'Storage Blob Data Contributor' role on the storage account. — The 'azure/storage-blob-upload' action requires the service principal used for OIDC authentication to have the 'Storage Blob Data Contributor' role on the storage account to upload static website content. Without this role, the action fails to obtain credentials for blob write operations, resulting in the 'Failed to get credentials' error.

What should I do if I get this AZ-400 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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