What does "Azure B2C invalid property replyUrlsWithType" mean?

The error message "Azure B2C invalid property replyUrlsWithType" indicates that there is an issue with the way reply URLs (also known as redirect URIs) are configured in your Azure Active Directory B2C (Azure AD B2C) application registration. This usually arises when you're trying to register an application within Azure B2C, and there's a mismatch or incorrect formatting in the reply URLs you've provided.

Here's a breakdown of what this error typically signifies:

1. Incorrect Format: The 'replyUrlsWithType' property expects a specific JSON format when using the Azure AD Graph API or similar methods to update the application registration. If the JSON structure is malformed, this error can occur.

2. Invalid URL: The provided reply URLs may not adhere to the required URL format (e.g., missing scheme like 'https://' or containing invalid characters).

3. Mismatch with Allowed URLs: The reply URLs you are trying to add might not match the allowed patterns configured in the Azure AD B2C tenant or might conflict with existing configurations.

4. Missing or Incorrect Type: The 'replyUrlsWithType' property requires specifying the type of the reply URL (e.g., 'Web', 'Spa', 'Native'). Omitting or misconfiguring this type can lead to the error.

To resolve this issue, consider the following steps:

a. Verify the URL Format: Ensure that all reply URLs are correctly formatted, including the 'https://' scheme for production environments. For example, https://your-app.com/signin-oidc.

b. Check the JSON Structure: If you're using an API to update the reply URLs, confirm that the JSON structure is correct. The 'replyUrlsWithType' property should contain an array of objects, each with a 'url' and a 'type' field.

An example of a correct JSON structure might look like this:

{
  "replyUrlsWithType": [
    {
      "url": "https://your-app.com/signin-oidc",
      "type": "Web"
    }
  ]
}

c. Use Azure Portal: Whenever possible, use the Azure portal to manage reply URLs. The portal provides a user-friendly interface and often handles the formatting correctly.

d. Permissions: Ensure that the application or service principal used to update the application registration has the necessary permissions to modify the 'replyUrlsWithType' property.

e. Application Type: Make sure you are configuring the Reply URLs appropriate to your application type (Web, SPA, Native).

By carefully reviewing and correcting the reply URL configurations, you should be able to resolve the "Azure B2C invalid property replyUrlsWithType" error and successfully register your application in Azure AD B2C.

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