title: Key Vault reference in Azure App Service doesn't resolve
body: <p>I have an ASP.NET (.NET 6) application hosted within an Linux app service plan.
  I'm attempting to reference a Key Vault secret within the configuration settings using the following syntax: <code>@Microsoft.KeyVault(SecretUri=https://redacted.vault.azure.net/secrets/test/version)</code></p>
  <p>However, I just get a red-cross next to the setting inside Configuation blade in the Azure Portal. If I open up the setting, then I get no further information about the issue.</p>
  <p>Here's what I have done so far:</p>
  <ul>
  <li>Followed the instructions at <a href="https://docs.microsoft.com/en-us/azure/app-service/app-service-key-vault-references" rel="nofollow noreferrer">https://docs.microsoft.com/en-us/azure/app-service/app-service-key-vault-references</a></li>
  <li>I have used the 'Key Vault Application Settings Diagnostics' tool inside the 'Diagnose and solve problems' blade; this told me everything was fine with green ticks across multiple checks EXCEPT at the bottom it came up with the following amber warning with no further information:-</li>
  </ul>
  <blockquote>
  <p>Uncategorized issues found</p>
  </blockquote>
  <ul>
  <li>I have configured the ap service managed identity and given the appropriate permissions to the principal inside Key Vault</li>
  <li>I have enabled 'Allow access from trusted Microsoft services' inside the Key Vault firewall.</li>
  </ul>