Check in /var/run/log/esxupdate.log file, better to run the following and let it write the logs to a temporary file.

tail -f /var/log/esxupdate.log > /tmp/esxupdate.log

It will have error like:

> cat /tmp/esxupdate.log | grep -i 'error'  
2025-08-12T09:44:57Z Er(11) esxupdate[2109082]: An esxupdate error exception was caught:  
2025-08-12T09:44:57Z Er(11) esxupdate[2109082]: esxutils.EsxcliError: Errors:  
2025-08-12T09:44:57Z Er(11) esxupdate[2109082]: Error getting data for filesystem on '/vmfs/volumes/67c5a845-d967bb36-da89-0025b502014f': Cannot open volume: /vmfs/volumes/67c5a845-d967bb36-da89-0025b502014f, skipping.  
2025-08-12T09:44:57Z Er(11) esxupdate[2109082]: esximage.Errors.InstallationError: Failed to query file system stats: Errors:  
2025-08-12T09:44:57Z Er(11) esxupdate[2109082]: Error getting data for filesystem on '/vmfs/volumes/67c5a845-d967bb36-da89-0025b502014f': Cannot open volume: /vmfs/volumes/67c5a845-d967bb36-da89-0025b502014f, skipping.

Fix is to remap the LUN. The issue is that the LUN may be in use.

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references:

Patching an ESXi host fails with error “esxupdate returned with exit status: 15”