When getting head from tls enabled registry, I get "x509: certificate signed by unknown authority"

[hyeoncheolkim91]

Hi
When I tried to setup watchtower that connects to private registry, It was able to pull image and update the container. But in my logs with debug mode, there is error:
x509: certificate signed by unknown authority" when it tries to get head from registry.
Is this error expected?

time="2024-09-05T03:14:40Z" level=debug msg="Checking if pull is needed" container=/api image="10.99.3.243:3443/api:latest"
time="2024-09-05T03:14:40Z" level=debug msg="Built challenge URL" URL="https://10.99.3.243:3443/v2/"
time="2024-09-05T03:14:40Z" level=debug msg="Could not do a head request for "10.99.3.243:3443/api:latest", falling back to regular pull." container=/api image="10.99.3.243:3443/api:latest"
time="2024-09-05T03:14:40Z" level=debug msg="Reason: Get "https://10.99.3.243:3443/v2/\": x509: certificate signed by unknown authority" container=/api image="10.99.3.243:3443/api:latest"