When using an EC2 instance within AWS, the hostname is not set by default. Therefore, the following call will throw an exception:

InetAddress localhost = InetAddress.getLocalHost();
return localhost.getHostName();

Previously, logback handled this by using the following code:

try {
    InetAddress localhost = InetAddress.getLocalHost();
    return localhost.getHostName();
} catch (UnknownHostException e) {
    return getLocalAddressAsString();
}

However, this commit reverted those changes:
https://github.com/qos-ch/logback/commit/c2dcbfcfb4048d11d7e81cd9220efbaaccf931fa#diff-5272ed59e3fd3a8248d58fe2bdb38930

Can we please re-add the code to appropriately handle unknown hostname. Based on the commit description, it looks like this was done in error.