The Proxy server error occures when starting dotdocker - docker

Question

The following error occurs when I start the dotdocker sudo dotdocker start for my project. There was no error before and it was working successfully. However, this error appeared without any changing on the project code. The version of docker-compose and dotdocker are 1.21.2 and 1.4.2 respectively. I tried several things to solve the problem but nothing is working such as::
1 - sudo dotstart stop
2 - sudo systemctl restart NetworkManager
3 - sudo service docker restart
❯ Start dotdocker containers
❯ Start proxy
↓ Pulling codekitchen/dinghy-http-proxy:latest [skipped]
→ Image already exists
↓ Creating dotdocker-proxy [skipped]
→ Container already created
✖ Starting dotdocker-proxy
→ (HTTP code 500) server error - driver failed programming external conn
…
✔ Start dnsmasq
Setting up DNS
(node:4314) UnhandledPromiseRejectionWarning: Error: (HTTP code 500) server error - driver failed programming external connectivity on endpoint dotdocker-proxy (4e8078f31f05224f8041e65026e179114701636bbd13eb71a67382ccae860db9): Error starting userland proxy: listen tcp 0.0.0.0:80: bind: address already in use
at /usr/local/lib/node_modules/dotdocker/node_modules/docker-modem/lib/modem.js:257:17
at getCause (/usr/local/lib/node_modules/dotdocker/node_modules/docker-modem/lib/modem.js:287:7)
at Modem.buildPayload (/usr/local/lib/node_modules/dotdocker/node_modules/docker-modem/lib/modem.js:256:5)
at IncomingMessage.<anonymous> (/usr/local/lib/node_modules/dotdocker/node_modules/docker-modem/lib/modem.js:232:14)
at IncomingMessage.emit (events.js:326:22)
at endReadableNT (_stream_readable.js:1244:12)
at processTicksAndRejections (internal/process/task_queues.js:80:21)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:4314) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
(node:4314) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Answer 1

I haven't used the dotdocker but from what I see from the error and specifically this part:
tcp 0.0.0.0:80: bind: address already in use
Something in your system is already using port 80 that your program wants to use.
In order to see what is using port 80 you can try:
lsof -P -S 2 -i "tcp:80" | grep "\(:80->.*:\|:80 (LISTEN)$\)"
This will give you the info and the process id in the second column.
For example:
apache2 1914 root 4u IPv6 11920 0t0 TCP *:80 (LISTEN)
You can then kill this process that occupying the port you want to use by:
kill -KILL 1914