This happened to me today and thought it was worth sharing.  Most of the hosts in this particular cluster upgraded fine to ESXi 6u2 from ESXi 5.5u3 with the exception of this one host.  Update manager kept giving me this error “Cannot run upgrade script on host” in the vCenter Recent Tasks pane.

A quick google search brought me to this KB article 2007163, but after following the KB I wasn’t able to find the referenced error “Remediation failed due to non mode failure “on the update manager server (Win2008) under C:\AppData\VMware\Update Manager\Logs\vmware-vum-server-log4cpp.log file.

I started an SSH session to the ESXi host, but wasn’t able to find and entry similar to the error “OSError: [Errno 39] Directory not empty:” in the /var/log/vua.log file

I instead found this error:

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[FFD0D8C0 error ‘Default’] Alert:WARNING: This application is not using QuickExit().

The exit code will be set to 0.@ bora/vim/lib/vmacore/main/service.cpp:147

–> Backtrace:

–> backtrace[00] rip 1bc228c3 Vmacore::System::Stacktrace::CaptureFullWork(unsigned int)

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By chance, I happened to check space on the ESXi host #df -h and found I had a partition that was 100% full.

So I changed directory to it # cd /storage/core/……./ where I found two more directories  /var/core/ .  Using the command #ls to list the directory, I found two zdumps.

I deleted the two zdumps, and then checked the space again #df -h

Seeing now that my directory is now 68% utilized instead of 100%, I attempted the ESXi 6u2 upgrade again this time with success.