While updating the VMware ESXi 7.0 U2 host to ESXi 7.0 U2c, the upgrade might fail and the following entries might be logged in the esxupdate.log file:
2021-10-29T14:11:21Z esxupdate: 2102510: esxupdate: ERROR: File /tmp/esx-update-2102510/lib64/python3.8/site-packages/vmware/esximage/Transaction.py, line 928, in checkBaseImageUpgrade
2021-10-29T14:11:56Z esxupdate: 2102510: esxupdate: ERROR: esximage.Errors.InstallationError: This upgrade transaction would skip ESXi Base Image VIB(s) VMW_bootbank_i40en_1.11.1.31-1vmw.703.0.0.49537716, which could cause failures post upgrade. Please use an alternative upgrade method that would install the above VIB(s). For example, use an image profile instead of VIBs to perform the upgrade.
This is a known issue with upgrades. Refer to the following VMware knowledgebase article: https://kb.vmware.com/s/article/85982.