Azure AD B2C无缝用户迁移自定义策略调用On-Prem API验证密码时出现验证失败错误的排查求助

Hi Shiva, let’s break down the common culprits behind the "Unable to validate the information provided" error when using an on-prem API for password validation in Azure AD B2C custom policies. Here’s what to check step by step:

• Double-check the ServiceUrl in your API’s technical profile metadata to ensure it’s correct and accessible to Azure AD B2C (no firewall or NSG rules blocking inbound traffic from B2C’s IP ranges).
• If using ClientCertificateAuthentication, confirm the certificate is uploaded correctly to your B2C tenant’s key container, its thumbprint matches the value in the policy, and it’s not expired. For BasicAuthentication, ensure the username/password stored in your B2C keys are accurate and the policy references the correct key ID.
• Test your API directly with a tool like Postman using the exact request B2C would send. Azure AD B2C expects a 200 OK response for successful validation—any non-200 status code (401, 403, 500, etc.) will trigger this error.

• Ensure your technical profile’s InputClaims correctly map user inputs (like signInName and password) to the parameters your API expects. Mismatched parameter names will cause the API to fail processing the request.
• Check that your API’s response follows the format B2C expects. For successful validation, return a valid JSON response (no syntax errors) with any required claims. For failed validation, return an error payload that B2C can interpret (avoid malformed JSON, which will also trigger the generic validation error).
• Confirm OutputClaims in the policy match the keys in your API’s response—incorrect mappings can lead to unexpected failures even if the API itself works.

• Make sure the technical profile calling your API is included in the correct step of your user journey (e.g., right after the local account sign-in step for password validation). If it’s placed in the wrong phase, the necessary claims (like password) might not be available yet.
• Review any claim transformations applied to password or signInName before the API call. Accidental modifications (like trimming, encoding errors) can send invalid values to your API, causing validation to fail.

• Enable Application Insights for your B2C tenant and check the logs for specific error details. Look for entries like ApiConnectorErrorMessage or TechnicalProfileExecutionError—these will often reveal the root cause (e.g., API timeout, authentication failure, invalid response format).
• Check your on-prem API’s own logs to confirm if B2C’s requests are reaching it, and if so, what errors occurred during processing (e.g., password hash mismatch, user not found in your on-prem system).

• Ensure you’re using the latest version of the Azure AD B2C base policies. Older versions may have known issues with API connectors, so updating your TrustFrameworkBase.xml and TrustFrameworkExtensions.xml to the latest release can resolve unexpected errors.

If you still hit issues after checking these points, sharing the relevant sections of your policy (like the API technical profile) and specific logs from Application Insights would help narrow things down further.

内容的提问来源于stack exchange，提问作者Shiva Prasad Pola