If you have a vCenter added to your veeam inventory, from time to time you'll need to refresh the vCenter certificate. This will need to happen after the vCenter certificate is updated or changed.
In Veeam, you may see an error similar to this:
13/08/2023 3:59:55 PM :: Host vcs.hadraas.servercontrol.com.au is not available. Error: The remote certificate is invalid according to the validation procedure. To refresh the vCenter certificate, first connect to your Veeam server via local console or RDP, then follow the below steps:
Navigate to 'Backup Infrastructure' and within Managed Servers -> VMware vSphere -> vCenter Servers -> Right+click on vcs.hadraas.servercontrol.com.au -> Properties:
Click 'Finish' on the dialogue box that appears. This will prompt Veeam to re-scan the vCenter and update it's certificate.
That's it! Veeam will now trust the new vCenter certificate.