Environment:

• Cloud: Azure
• Databricks Account Console (accounts.azuredatabricks.net)
• Access Connector: system-assigned managed identity (no user-assigned identity involved)
• Region: East US

Issue:

Creating a Unity Catalog storage credential via the Account Console UI, using an Access Connector with a system-assigned managed identity, fails with:

BAD_REQUEST: Azure Managed Identity Credential with Access Connector Id <id>and Managed Identity ID:  for Account Id: <account-id> could not be found.

Root cause:

Checked the network tab — the UI sends:

"azure_managed_identity": {
  "access_connector_id": "<connector-id>",
  "managed_identity_id": ""
}

For system-assigned identities, managed_identity_id shouldn't be sent at all (per Databricks docs). The backend seems to treat the empty string as "look up this identity," fails, and returns a misleading error blaming the connector.

Proof it's UI-side, not config:

Everything on Azure was verified correct (connector exists, region matches, RBAC correct, waited 1hr+ for propagation, tested with a proper Global Admin account). Running the same request via CLI, omitting managed_identity_id entirely, worked on the first try — same connector, same subscription, no Azure-side changes.

databricks account storage-credentials create <metastore-id> --json '{  "credential_info": {    "name": "cred",    "azure_managed_identity": {"access_connector_id": "<connector-id>"}  }}'

Is this a known bug in the Account Console UI for system-assigned Access Connectors?