Intermittent Access Issue Between Azure Function App and Key Vault (Private Endpoint Enabled)

We have an Azure Function App configured to retrieve secrets from Azure Key Vault using Managed Identity, following the recommended pattern.

Key details of our setup:

• The Function App is running on a Premium Plan and VNet-integrated.
• The Key Vault has Public Network Access disabled and uses a Private Endpoint.
• The Function App accesses Key Vault secrets through Key Vault references in application settings.

We are intermittently observing issues where the Function App fails to access the Key Vault. Under the “Diagnose and Solve Problems” blade, the following error appears:

[ResolveWorkitem] AccessToKeyVaultDenied error while retrieving Key Vault Secret Reference 
microsoft.KeyVault(SecretUri=*********************). 
Exception: KeyVaultResolver.Common.ReferenceResolverException: 
Exception of type 'KeyVaultResolver.Common...'

Has anyone encountered this issue or found a reliable way to resolve intermittent connectivity/authentication failures between a Function App and a Key Vault over a private endpoint?