VM becomes unresponsive with "Another task is already in progress" error due to oversized snapshot

Products

• VMware vSphere ESXi
• VMware vCenter Server

Issue/Introduction

One of the virtual machines becomes unresponsive during routine operations. Attempts to shut down the VM or create/remove snapshots fail with the error message:

"Another task is already in progress."

This blocks further administrative tasks and affects normal VM operations

Cause

During the scheduled backup activity, the backup solution creates a snapshot on the VM but fails to delete it post-completion. Over a period of time, this snapshot grows significantly—reaching over 2 TB in size. Due to the stale snapshot chain and underlying task lock, the VM becomes unresponsive, and common actions like shutdown or snapshot deletion throw errors.

Resolution

1. Refer to the Broadcom Knowledge article Powering off an unresponsive virtual machine on an ESXi host to identify and cancel the stuck task. This helps release any backend lock on the VM.

2. Restart the management agents Restarting Management Agents in ESXi on the ESXi host. This can help reset host-side services and clear stale states.

3. If the above methods do not help, migrate or shut down all VMs on the affected ESXi host. Then, log in to the host via iLO/DRAC and perform a COLD Boot to reset the host state fully to get rid of the stale vm process.

4. Try excluding the VM from the backup schedule to see if the lock is released, then attempt to remove the snapshot.
   
   
5. If the issue still persists, restoring the VM from a recent backup or cloning the VM is recommended.

For best practices regarding VMware snapshot usage and cleanup, refer Broadcom Knowledge article  Best practices for using VMware snapshots in the vSphere environment