What does this error indicate?

[agrajag (Todd Grayson)]

This is still being looked at in the background, FYI. The discussion is leading into the underlying connection components that are within go.

For folks evaluating the connection setup and error, it is (I just made up this notation):

[Browser] --(https)--> Caddy [reverse proxy rule] --(http)/ERROR {client disconnect*}--> rejetto HFS server 

…with the context of the {client disconnect} being investigated as to where its initiating from. HTTP/2 in GO is emitting the error (click “find references” in that link) the client in that error message of:

http.log.error readfrom tcp 127.0.0.1: 53845->127.0.0.1: 81: client disconnected

This is taking a bit to sort out, the tcpdump / wireshark evaluation would help. If this starts to happen again and repeats please capture and share connection resets or other tcp anomalous behavior (red/black lines in the wireshark traffic), and please let us know if it does not.

[agrajag (Todd Grayson)]

You might want to check out the keepalive directive as well for the reverse proxy config? Check out this discussion:

Mqtt/tcp keepalive when proxying websocket

No, this is a great way to do it. Simplifies a bunch of stuff client-side IMO (for general WS, in my experience, can’t comment on MQTT cause I don’t use it). There’s some keepalive options you can play with in the reverse_proxy's HTTP transport: I’ve never needed to play around with changing keepalives, so I don’t have any specific recommendations there. But this is for the connection between Caddy and your upstream. This thread mentions this was added to ListenConfig, which seems like a…

[JustinWebDev (Justin WD)]

I added keepalive, but no change. I noticed that I get 5.4MB of the file but that’s it when this issue happens.

The web_access.log was not created. Is it preempted by the caddy-log directive?

{
	log caddy-log {
		output file caddy.log
	}
}
web.thedomain.com:8443 {
	reverse_proxy :81 {
		transport http {
			keepalive 120s
		}
	}
	tls {
		protocols tls1.3
	}
	log {
		output file D:\BIN\caddy\web_access.log {
			roll true # Rotate logs, enabled by default
			roll_size_mb 5 # Set max size 5 MB
			roll_local_time true # Use localhost time
			roll_keep 2 # Keep at most 2 log files
			roll_keep_days 7 # Keep log files for 7 days
		}
	}
	header / Strict-Transport-Security "max-age=63072000"
}