• You cannot remediate an ESXi 5.x/6.x host.
• Remediation of an ESXi 5.x or 6.x host using vCenter Update Manager fails.
• You see the error:
  
  The host returns esxupdate error code:15. The package manager transaction is not successful. Check the Update Manager log files and esxupdate log files for more details

To resolve the issue, repair the altbootbank partition.

1. Run this command to determine the device for /altbootbank:
   
   # vmkfstools -P /altbootbank
   
   You see output similar to:
   
   mpx.vmhba32:C0:T0:L0:5
    
2. Run this command to repair the altbootbank filesystem:
   
   # dosfsck -a -w /dev/disks/device_name
   
   For example:
   
   # dosfsck -a -w /dev/disks/mpx.vmhba32:C0:T0:L0:5
   
   For non-local storage, the device may be called something like "naa.60a98000443331744f5d444a6d71724e:6", so command would then be:
   
   # dosfsck -a -w naa.60a98000443331744f5d444a6d71724e:6
   
   Note that we always include the partition number in the command, in this case, ":6"
   
   If dosfsck reports 'Root folder out of space':
           Move or delete the .REC files generated in the altbootbank folder and run the repair operation again to complete the process.
   
   If dosfsck reports "Input/output error":
           Disk health is likely bad and likely the vendor for the disk or storage array needs to be consulted.
    
3. If remediation fails at this stage, reboot the host.
4. If remediation continues to fail, a restart of the vSphere Update Manager service may be required.

• -a – Indicates automatically repair the filesystem
• -w – Writes changes to the disk immediately