Terraform keeps track of the infrastructure state via the state file. When you initially ran terraform plan, Terraform determined that the port should be changed from80 to 443. However, since another team member manually modified the load balancer, Terraform's local state file is now outdated.

When you run terraform apply, Terraform willcompare the expected state (from the plan) with the actual state (from the provider API).

Since the port is already set to443, but the local state file still shows80, Terraform willfail with an errordue to the state mismatch.

To resolve this, you should run terraform refresh or use terraform apply -refresh-only to update the local state before applying changes.

Official Terraform Documentation Reference:

State Management - HashiCorp Documentation

Managing Drift in Terraform