Docker: "driver failed programming external connectivity on endpoint testcontainer"
For clarity, the answer that worked for me from the thread linked in the comment section is:
# Enter below command, it will clear all chains.$ sudo iptables -t filter -F$ iptables -t filter -X# Then restart Docker Service using below comamnd$ systemctl restart dockerhttps://github.com/moby/moby/issues/16816#issuecomment-327074574