Insufficient system resources exist to complete the API during Active Directory replication

Products

• VMware vSphere ESXi

Issue/Introduction

You observe the following symptoms within your Active Directory (AD) environment:

• Active Directory replication fails between Domain Controllers across different sites or data centers.
• You receive Kerberos error: Insufficient system resources exist to complete the API (0xc000009a).
• You receive error: 14 (0xe): Not enough memory resources are available to complete this operation.
• The Knowledge Consistency Checker (KCC) fails to build replication topologies.
• Domain Controller virtual machines show abnormal memory consumption (e.g., up to 8GB on affected nodes) and isolated memory blocks.
• Infrastructure monitoring and host-level packet captures on the ESXi host show no networking interference or hardware anomalies.

Environment

• VMware ESXi
• Microsoft Windows Server (Domain Controller role)
• Windows Credential Guard enabled

Cause

This issue occurs because Windows Credential Guard consumes abnormal amounts of memory and isolates memory blocks on the Guest OS. This resource exhaustion prevents the Knowledge Consistency Checker (KCC) from building replication topologies and results in Kerberos authentication failures. The hypervisor and underlying network infrastructure remain stable, indicating the bottleneck is isolated to the Guest OS configuration.

Resolution

Too resolve this issue, you must address the resource exhaustion caused by the third-party security feature:

1. Follow Microsoft-documented procedures to troubleshoot or disable Windows Credential Guard on the affected virtual machines.
2. Verify that memory utilization stabilizes (typically dropping from GB-level consumption back to MB-level for the specific security process).
3. Force an Active Directory replication sync to confirm the connection between servers is restored.

If you require a permanent fix that allows Credential Guard to remain enabled, consult Microsoft Support for the latest OS patches or configuration requirements for Credential Guard in your specific environment.