Storage vmotion for VM fails with error "Error caused by file /vmfs/volumes/vsan:xxxxxxxxxxxxx-xxxxxxxxxxxxx/xxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxxx/test.vmdk" due to checksum issues.

Products

• VMware vSAN

Issue/Introduction

Symptoms:

• The storage vmotion is failing with checksum mismatch error. Skyline health indicates vSAN is healthy.
  
  
• Storage vmotion failing with Checksum mismatch between vSAN datastore.
  
  
• The following error is observed in vSphere Web Client/UI Page. 
  
  Error message :

Failed waiting for data. Error 195887167. Connection closed by remote host, possibly due to timeout. 2025-07-03T19:48:49.447128Z Failed to copy source (/vmfs/volumes/vsan:xxxxx.vmdk) to destination (/vmfs/volumes/vsan:xxx/xxxx/xxxx.vmdk): Checksum mismatch. Failed to copy one or more disks. A fatal internal error occurred. See the virtual machine's log for more details. 2025-07-03T19:48:51.337343Z vMotion migration [xxxx] failed to read stream keepalive: Connection closed by remote host, possibly due to timeout

• The vmkwarning.log and vmkernel.log indicates storage vmotion migrate task failed due to checksum mismatch :

vmkernel.log:2026-01-13T04:26:23.389Z Wa(180) vmkwarning: cpu36:44343895)WARNING: Migrate: 257: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx S: Failed: Checksum mismatch (0xbad003a) @0x420016adc88f

vmkwarning.log:2026-01-13T04:26:23.389Z Wa(180) vmkwarning: cpu36:44343895)WARNING: Migrate: 257: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx S: Failed: Checksum mismatch (0xbad003a) @0x420016adc88f

Environment

VMware vSAN (All Versions)

Cause

The failure occurs because a vSAN object has encountered an unrecoverable medium or checksum error. The vSAN blocks I/O on the affected component to prevent data corruption, which causes backup, clone, consolidation, or migration tasks to fail.

Resolution

This issue can be resolved by creating a new vSAN storage policy with the Object checksum option disabled and applying that policy to the affected virtual machine. This configuration allows the migration to proceed by bypassing existing block-level checksum errors.

Procedure : 

Step 1: Clone vSAN Default Storage Policy

1. 1. Log in to the vSphere Client.

   2. Navigate to Menu > Policies and Profiles.

   3. Click on VM Storage Policies in the left sidebar.

   4. Select your existing vSAN storage policy (e.g., vSAN Default Storage Policy).

   5. Click Clone (or Actions > Clone).

   6. Name the policy: example :  vSAN-No-Checksum-Recovery.

   7. In the vSAN rules section:

      • Navigate to the Advanced Policy Rules tab.

      • Locate the Object checksum setting.

      • Change it from Enabled to Disabled.
        
        

   8. Complete the wizard and click Finish.

Step 2: Apply the New Policy to the Affected VM

Now assign this "No Checksum" policy to the VM that is failing to migrate.

1. 1. Navigate to Hosts and Clusters and select the affected VM.

   2. Right-click the VM and select VM Policies > Edit VM Storage Policies.

   3. In the VM storage policy dropdown, select your newly created vSAN-No-Checksum-Recovery policy.

   4. Click OK.

      • Note: vSAN will perform a background reconfiguration. Wait for the "Reconfigure VM" and "Update VM Storage Policy" tasks to complete.

   5. Check the Monitor > vSAN > Virtual Objects tab for that VM. Ensure the status shows as Healthy or Active (ignoring the checksum warning).

Step 3: Perform Storage vMotion and revert the VM storage policy back to original vSAN storage policy

With checksums disabled, vSAN will no longer block the read operation on the "bad" block, allowing the migration to proceed.

1. 1. Perform Storage vmotion for the VM. 

   2. The migration should now complete without the checksum error.
      
      
   3. Once the storage vmotion is completed, change the storage policy of the VM back to Original Storage policy or vSAN default storage policy. 

Additional Information

For more information kindly refer :  VMware vSAN disk encounters medium errors but not failed out by vSAN