I have been struggling with a strange issue(bug?) with Phoenix 1.4 and channels.
It only occurs (I think) when accessing the server from a remote connection.
i.e. When using a macbook or Ubuntu workstation deskop in DEV mode locally I dont see the error.
When I deploy to a remote, cloud vm, i.e. Linode, and run in DEV or PROD mode, I get the error.
My main/original project was working with Phoenix 1.4 (master) on PROD Linode maybe 6 to 8 weeks ago, but now it only runs in local mode.
I replicated the issue/bug with Chris Mccords canonicalish Phoenix Chat Example.
I posted the issue
and the forked Phoenix Chat Example code is
apologies if I have missed something super obvious