`wrangler dev` crashes and/or hangs while attempting to perform local network development with `--ip` on macOS with Firewall enabled

[jGowgiel]

What versions & operating system are you using?

Wrangler 4.22.0 - macOS Sequoia 15.5

Please provide a link to a minimal reproduction

Any project created from latest

Describe the Bug

I've run into a few bugs while attempting to work around macOS Firewall restrictions for local network connections, and have identified a few hangs and crashes while doing so.

Some of these steps are ones that I've only pieced together myself and don't have a full understanding of, but it seems as if they should be working and the errors I'm observing are definitely not normal.

• On macOS, with the System Settings "Firewall" up (and no additional configuration) wrangler dev --ip 192.168.x.x (substituting the current machine's IP address) will result in repeated debug-level errors like so:

workerd/io/io-context.c++:377: info: uncaught exception; exception = workerd/jsg/_virtual_includes/iterator/workerd/jsg/value.h:1565: disconnected: jsg.Error: Network connection lost.
stack: 1017f61d0 1017f6d8e 1035d660f 10162e2b0 10162e770
workerd/jsg/util.c++:322: info: exception = kj/async-io.c++:60: disconnected: stream disconnected prematurely
stack: 1035e36a7 1035e38ba 1035d660f 101ebbc67 101ebc783 101ebea6a 101e9f790 101ea63a0 101eb8df0 100fd6540 1018391c0 101731b30
✘ [ERROR] workerd/io/worker.c++:2126: info: uncaught exception; source = Uncaught (in promise); stack = Error: Network connection lost.

Without --log-level debug, the CLI appears to hang while being nonfunctional. I'd expect here that the CLI would at least error out, as it isn't actually able to connect to the network in a meaningful way.

• On macOS, with the System Settings "Firewall" up but having configured node_modules/@cloudflare/workerd-darwin-64/bin/workerd as being allowed to accept incoming connections (e.g. sudo /usr/libexec/ApplicationFirewall/socketfilterfw --add /home/projectname/node_modules/@cloudflare/workerd-darwin-64/bin/workerd) wrangler dev --ip 0.0.0.0 does startup, but the first request to the local address (192.168.x.x:8787) causes a silent crash like so:

*** Fatal uncaught kj::Exception: kj/async-io-unix.c++:1365: failed: setsocketopt(IPPROTO_TCP, TCP_NODELAY): Invalid argument
stack: 1032073f6 103207835 1031d060f 100c3c52e 100c3d2ba 100c40d3b 100c41573 100c41eca 100bdb1e3 10322b59a 10322b9bb 103229ec8 103229be0 100bc8bd6 20644852f

Here as well, the CLI appears to hang - the above error is only visible with --log-level debug. I would expect this configuration (allowing the workerd process to accept incoming connections and starting with --ip 0.0.0.0) to allow other devices to connect to the running process, but this exception appears to keep that from working.

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Workarounds

Disabling the macOS Firewall entirely appears to fix the issue, but feels unsafe.

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Impact

In combination, these two issues mean that it isn't possible to use wrangler dev --ip on macOS to serve a local Cloudflare worker to other devices on the local network, without entirely disabling the macOS Firewall on the host machine. At least, I haven't found a way to do so.

Please provide any relevant error logs

wrangler-2025-06-28_18-48-47_473.log

wrangler-2025-06-28_18-49-13_723.log

[jGowgiel]

I attempted the same fix as #4763 but in my case, it didn't work.