The most frequent culprits for port 443 occupation on a Windows server include:
Let's dive deep into the issue of port 443 being occupied by another application when trying to use it for Veeam Backup replication. The most frequent culprits for port 443 occupation
If reconfiguration isn't feasible, you can temporarily stop the conflicting service during Veeam installation or upgrade. One user successfully tested this approach: "I was able to temporarily disable the service using 443 and successfully complete the upgrade to v13". No—if you temporarily stop the conflicting service, Veeam
No—if you temporarily stop the conflicting service, Veeam services will fail again when that service restarts and reoccupies port 443. Because port 443 is hardcoded into the API
When upgrading to Veeam Backup & Replication (VBR) v13 is a strictly required, hardcoded dependency for the new Veeam Web Service/API Gateway
A: Only when communicating with a Veeam Backup & Replication server. The agent itself does not listen on 443.
Because port 443 is hardcoded into the API gateway of modern VBR platforms, trying to force-change Veeam's ports inside the registry can completely break communication to the console and identity components. If you cannot change the port configuration of the conflicting application permanently, use one of the architectural workarounds below: Implementation Concept