How to Configure keyVaultReferenceIdentity in Azure App Service?

Overview This guide shows you how to fix a critical Azure App Service configuration issue where the keyVaultReferenceIdentity property is hidden from the Azure Portal but required for accessing Key Vault secrets. Symptoms Developers encountering this issue typically observe: Key Vault references returning empty values instead of secret content Configuration entries showing "Not Resolved" error messages Application settings failing to fetch secret values from Key Vault Authentication errors when attempting to access protected secrets 401/403 errors from App Service attempting to validate Key Vault access Why This Happens Azure App Service uses Managed Identity authentication to access Key Vault secrets, but the keyVaultReferenceIdentity property is deliberately hidden from standard Azure Portal interfaces. This property only exists at the Azure Resource Manager (ARM) level, making it invisible through the typical Azure management UI. Technical Architecture App Service → Managed Identity → Azure AD → Key Vault Access Policy → Secret Store App Service attempts to authenticate using its assigned Managed Identity Azure needs explicit permission through the keyVaultReferenceIdentity property This permission exists only in the underlying ARM configuration Without this configuration, the authentication chain breaks Key Vault references resolve to empty values or error messages Why Portal Visibility is Limited Microsoft implements this design choice for several reasons: Security : Keeps identity-to-Key Vault mappings out of standard management interfaces Simplicity : Prevents accidental misconfigurations that could cause security issues Audit Trail : Ensures all identity configurations go through proper change management Resource Provider : Some properties require ARM-level configuration for consistency Prerequisites Required Azure Resources Azure Subscription : Active subscription with appropriate permissions Azure App Service : Existing Linux or Windows App Service User-As