websocket protocol: 'upgrade' token not found in 'Connection' header"

[w33dw0r7d]

I build outline with caddy from commit: 5522935
And run inside container with config:

---
logging:
  logs:
    default:
      level: "INFO"
      encoder:
        format: console
apps:
  http:
    servers:
      "HOSTNAME":
        listen:
          - :443
        routes:
          - match:
              - host:
                - HOSTNAME
              - path:
                - /PATH/tcp
            handle:
              - handler: websocket2layer4
                type: stream
                connection_handler: ss1
          - match:
              - host:
                -  HOSTNAME
              - path:
                - /PATH/udp
            handle:
              - handler: websocket2layer4
                type: packet
                connection_handler: ss1

        trusted_proxies:
          source: static
          ranges:
            - 127.0.0.1
            - ::1
        client_ip_headers:
          - "X-Forwarded-For"
          - "X-Original-Forwarded-For"
          - "Forwarded-For"
          - "Forwarded"
          - "Client-IP"
          - "CF-Connecting-IP"
          - "X-Real-IP"
          - "X-Client-IP"
          - "True-Client-IP"

  layer4:
    servers:
      "1":
        listen:
          - "tcp/127.0.0.1:9000"
          - "udp/127.0.0.1:9000"
        routes:
          - handle:
              - handler: outline
                connection_handler: ss1
  outline:
    shadowsocks:
      replay_history: 10000
    connection_handlers:
      - name: ss1
        handle:
          handler: shadowsocks
          keys:
            - id: USER
              cipher: chacha20-ietf-poly1305
              secret: PASSWD

all work but sometimes i have a connection issue. Server throw this in logs:

2025/08/01 12:37:01.807 ERROR    http.handlers.websocket2layer4  failed to upgrade       {"err": "websocket: the client is not using the websocket protocol: 'upgrade' token not found in 'Connection' header"}
github.com/Jigsaw-Code/outline-ss-server/outlinecaddy.WebSocketHandler.ServeHTTP
        github.com/Jigsaw-Code/outline-ss-server/outlinecaddy@v0.0.1/websocket2layer4_handler.go:124
github.com/caddyserver/caddy/v2/modules/caddyhttp.wrapMiddleware.func1.1
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/routes.go:331
github.com/caddyserver/caddy/v2/modules/caddyhttp.HandlerFunc.ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/caddyhttp.go:74
github.com/caddyserver/caddy/v2/modules/caddyhttp.RouteList.Compile.wrapRoute.func1.1
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/routes.go:298
github.com/caddyserver/caddy/v2/modules/caddyhttp.HandlerFunc.ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/caddyhttp.go:74
github.com/caddyserver/caddy/v2/modules/caddyhttp.(*Server).enforcementHandler
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/server.go:481
github.com/caddyserver/caddy/v2/modules/caddyhttp.(*App).Provision.(*Server).wrapPrimaryRoute.func2
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/server.go:457
github.com/caddyserver/caddy/v2/modules/caddyhttp.HandlerFunc.ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/caddyhttp.go:74
github.com/caddyserver/caddy/v2/modules/caddyhttp.(*Server).ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/server.go:370
net/http.serverHandler.ServeHTTP
        net/http/server.go:3301
net/http.(*conn).serve
        net/http/server.go:2102

Client on iOS Version 1.15.2 (484997)

[kriakiku]

+1 Same

[jyyi1]

Thanks for reporting this issue. The following error message indicates a missing Upgrade header in the incoming request, can you double confirm that?

{"err": "websocket: the client is not using the websocket protocol: 'upgrade' token not found in 'Connection' header"}

[kriakiku]

Yes. I also think it’s related to the client-side error:

Client:

ProxyConnectionFailure: Failed to connect to server [SERVER_NAME].
Cause:   ERR_PROXY_SERVER_READ_FAILURE: failed to read HTTP HEAD response from the server
  Cause:     ERR_INTERNAL_ERROR: failed to read salt: read tcp [CLIENT_VLAN_IP]:58760->[SERVER_IP]:443: i/o timeout

Server:

{
  "level": "error",
  "ts": 1754915313.4811542,
  "logger": "http.handlers.websocket2layer4",
  "msg": "failed to upgrade",
  "err": "websocket: the client is not using the websocket protocol: 'upgrade' token not found in 'Connection' header",
  "stacktrace": `
    github.com/Jigsaw-Code/outline-ss-server/outlinecaddy.WebSocketHandler.ServeHTTP
        github.com/Jigsaw-Code/outline-ss-server/outlinecaddy@v0.0.1/websocket2layer4_handler.go:124
    github.com/caddyserver/caddy/v2/modules/caddyhttp.wrapMiddleware.func1.1
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/routes.go:331
    github.com/caddyserver/caddy/v2/modules/caddyhttp.HandlerFunc.ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/caddyhttp.go:74
    github.com/caddyserver/caddy/v2/modules/caddyhttp.RouteList.Compile.wrapRoute.func1.1
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/routes.go:298
    github.com/caddyserver/caddy/v2/modules/caddyhttp.HandlerFunc.ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/caddyhttp.go:74
    github.com/caddyserver/caddy/v2/modules/caddyhttp.(*Server).enforcementHandler
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/server.go:481
    github.com/caddyserver/caddy/v2/modules/caddyhttp.(*App).Provision.(*Server).wrapPrimaryRoute.func2
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/server.go:457
    github.com/caddyserver/caddy/v2/modules/caddyhttp.HandlerFunc.ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/caddyhttp.go:74
    github.com/caddyserver/caddy/v2/modules/caddyhttp.(*Server).ServeHTTP
        github.com/caddyserver/caddy/v2@v2.10.0/modules/caddyhttp/server.go:370
    net/http.serverHandler.ServeHTTP
        net/http/server.go:3301
    net/http.(*conn).serve
        net/http/server.go:2102`
}