Cannot unmount the datastore after migrating the virtual machines

Products

• VMware vCenter Server

Issue/Introduction

• You are unable to unmount the datastore after migrating all the virtual machines from it.
• When trying to confirm in the Datastore Unmount dialog, you see a red X next to No virtual machine resides on the datastore.
• There are no ISOs or any virtual disks connected to any virtual machines from the datastore.

Environment

• VMware vCenter Server 5.x
• VMware vCenter Server 6.x
• VMware vCenter Server 7.x
• VMware vCenter Server 8.x

Cause

This issue occurs if a snapshot of any of the virtual machines attached to the datastore was taken before migrating the virtual machines to the new datastore.

Resolution

Delete the snapshots. Steps below:

1. Browse the datastore.
2. Go to the Virtual Machine tab and check if there are virtual machines running on the datastore.
3. If any of the virtual machines have a snapshot, delete it.
   
   To consolidate the snapshot files:
    
   1. Right-click the virtual machine and click Snapshot > Snapshot Manager.
   2. Click Delete All.