ESXi 6.x + Dell
The host returns esxupdate error code:99. An unhandled exception was encountered. Check the Update Manager log files and esxupdate log files for more details.
TL;DR
ssh root@host
esxcli software vib remove --vibname=OpenManage
Long version here: https://lonesysadmin.net/2016/05/27/esxupdate-error-code-99/
Thank you Bob
~~~