Port 4200 is already in use

Good afternoon

I am having a problem that has just started on any new ember apps created this morning. When I run ember serve I get Port 4200 is already in use, this also happens if I use a different port e.g. 8080.

This happens on my Macbook, a Centos VPS and a Ubuntu VPS. Am I missing a dependency or something else

Many Thanks


A few of us ran into the same problem; in fact, I asked this same question on the Discord > Help channel.

You should be able to find a fix here, thanks to people who are way smarter than I am:

Good luck!

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Thank you for you help, back up and running now

Same here, after a Ubuntu, Node and Ember fresh install, can’t run a new ember project normally. I can run using the --port 0 parameter but it gives me a very high port.

They still did not release a new version so maybe they are not aware of this issue.

Any resolution found for this?

Add this to your package.json until it’s fixed on their side:

"resolutions": {
  "ember-cli/portfinder": "1.0.21"
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Portfinder 1.0.23 has been released, which rolls back to 1.0.21. This should fix the issue. If you still have the problem, you might have locked to portfinder@1.0.22. Upgrade ember-cli to get the latest portfinder version in that case.

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