If you have trouble with vCenter and an upgrade is not possible then you proceeding with a manual upgrade on ESXi-Host.
- Download the needed patch on VMware webpage (https://my.vmware.com/group/vmware/patch#search).
- Upload the patch (ZIP-file) somwehre on your data store
- Enable SSH-service on your ESXi-host and establish a connection with SSH
- Execute the following command:
esxcli software vib install -d /vmfs/volumes/<your_datastore>/<your-patch-directory>/<your_patchfile.zip>
- Restart ESXi-Host