Update as of March 31, 2022: VMware has since released vSphere 7.0 U3d which replaces the 7.0 U3c release. It also appears that the 7.0 U3c release is no longer available in certain online repos, as well.
As of January 27, 2022, VMware has officially released vSphere version 7.0 U3c, and this particular release resolves a number of issues that were identified in previous U3 versions. In addition, the Apache log4j components have also been updated to version 2.17 to resolve both CVE-2021-44228 and CVE-2021-45046.
Please be sure to read the release notes carefully and work with your VMware TAM or account team, as upgrade guidance can vary based on the release you’re upgrading from. If you’re upgrading from version 6.5, 6.7, 7.0 GA, or 7.0 U1 to 7.0 U3c, this should be pretty straightforward; Upgrade vCenter Server first, and then upgrade your hosts.
However, if you’re upgrading from 7.0 U2c, 7.0 U2d, or prior releases of 7.0 U3, please read through the release notes and KB 87528 in thorough detail before upgrading. As mentioned in the release notes, there’s now a pre-check script called
vSphere_upgrade_assessment.py that should be used to determine if there are any ESXi hosts that require remediation before upgrading the vCenter Server.
In short, the reason behind this has to do with an Intel i40en (or i40enu) driver that was renamed between releases. In some cases, both drivers could exist on the same ESXi hosts, and this could lead to network communication errors. The aforementioned script checks to see if duplicate versions of this driver exist on the hosts. If the driver is found, it’s likely that the hosts will need to be upgraded before you can upgrade the vCenter Server. Also note that the script isn’t able to confirm or check hosts that may be in a disconnected or powered off state, so it’s best to ensure that everything is online and accessible when running this script.
vCenter Server 7.0 U3c | Build 19234570
Release notes: https://docs.vmware.com/en/VMware-vSphere/7.0/rn/vsphere-vcenter-server-70u3c-release-notes.html
ESXi 7.0 U3c | Build 19193900
Release Notes: https://docs.vmware.com/en/VMware-vSphere/7.0/rn/vsphere-esxi-70u3c-release-notes.html
Other Blogs and KBs related to the vSphere 7.0 U3c release announcement
Announcing Availability of vSphere 7.0 U3c (blog post):
vSphere 7 Update 3 – What’s New (blog post):
Using the vSphere_upgrade_assessment.py script | VMware KB 87258: https://kb.vmware.com/s/article/87258
Important list of Knowledge base articles identified for vSphere 7.0 U3c release | VMware KB 87327: https://kb.vmware.com/s/article/87327