# Observable Framework npm run dev fails with listen EINVAL on Fedora

## What was going on

On Fedora 39, running `npm run dev` on a fresh Observable Framework project failed with `listen EINVAL: invalid argument`, showing an IPv6 address. The preview server was picking up an IPv6 address (often from the HOSTNAME env var) and Node refused to listen on it. A maintainer pointed to PR #854 as the fix. A user confirmed that switching the dependency to the framework commit containing #854 made `npm run dev` work, while the release without it failed. So the fix is to use a framework version that includes PR #854.

## The fix that worked

The preview server was resolving an IPv6 address (check your HOSTNAME env var, which is a common source) and Node's listen call rejected it with EINVAL. Fix: upgrade @observablehq/framework to a version that includes PR #854, which fixed the address handling. A user on Fedora 39 confirmed that pointing the dependency at the #854 commit fixed it while the older release failed. Source: https://github.com/observablehq/framework/issues/812

## Where this came from

https://github.com/observablehq/framework/issues/812