I'm sending commands to different containers; this was working correctly until a few days ago. Since then, the only thing that changed is; a new Docker version was released and I switched from a TCP connection to a socket connection. Rest of the commands execute fine.

Information:

This environment runs inside of a virtual machine with Debian Jessie.

$ docker version
Client:
 Version:      1.11.0
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   4dc5990
 Built:        Wed Apr 13 18:17:17 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.11.0
 API version:  1.23
 Go version:   go1.5.4
 Git commit:   4dc5990
 Built:        Wed Apr 13 18:17:17 2016
 OS/Arch:      linux/amd64

$ docker info
Containers: 9
 Running: 6
 Paused: 0
 Stopped: 3
Images: 12
Server Version: 1.11.0
Storage Driver: aufs
 Root Dir: /var/lib/docker/aufs
 Backing Filesystem: extfs
 Dirs: 89
 Dirperm1 Supported: true
Logging Driver: json-file
Cgroup Driver: cgroupfs
Plugins: 
 Volume: local
 Network: bridge null host
Kernel Version: 3.16.0-4-amd64
Operating System: Debian GNU/Linux 8 (jessie)
OSType: linux
Architecture: x86_64
CPUs: 2
Total Memory: 1.963 GiB
Name: docker-host
ID: 4NGE:LLRW:4LEL:CE6Q:S7BN:UZ6Q:LA6K:4WHG:PNRI:LHAD:TWFW:WDBJ
Docker Root Dir: /var/lib/docker
Debug mode (client): false
Debug mode (server): false
Registry: https://index.docker.io/v1/
WARNING: No memory limit support
WARNING: No swap limit support
WARNING: No kernel memory limit support
WARNING: No oom kill disable support
WARNING: No cpu cfs quota support
WARNING: No cpu cfs period support

$ uname -a
Linux docker-host 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt25-1 (2016-03-06) x86_64 GNU/Linux

$ cat /etc/issue
Debian GNU/Linux 8 \n \l

Apr 21 07:35:46 docker-host docker[11709]: time="2016-04-21T07:35:46.790486036Z" level=error msg="attach: stdout: write unix /var/run/docker.sock->@: write: broken pipe"
Apr 21 07:35:46 docker-host docker[11709]: time="2016-04-21T07:35:46.931491694Z" level=error msg="Error running exec in container: attach failed with error: write unix /var/run/docker.sock->@: write: broken pipe\n"
Apr 21 07:35:46 docker-host docker[11709]: time="2016-04-21T07:35:46.931563085Z" level=error msg="Handler for POST /exec/fc6c278bc319d31ae125e6bfe62aab3bed6ae54d64223597e2c7a367fd540153/start returned error: attach failed with error: write unix /var/run/docker.sock->@: write: broken pipe"
Apr 21 07:35:46 docker-host docker[11709]: 2016/04/21 07:35:46 http: response.WriteHeader on hijacked connection
Apr 21 07:35:46 docker-host docker[11709]: 2016/04/21 07:35:46 http: response.Write on hijacked connection

Update: The problem occurs also when using a TCP connection: Update: When using a TCP connection there are less of these errors then when using a socket connection.

Apr 21 08:33:24 docker-host docker[25468]: time="2016-04-21T08:33:24.772961231Z" level=error msg="attach: stderr: write tcp 10.99.0.99:2375->172.17.0.2:40968: write: broken pipe"
Apr 21 08:33:25 docker-host docker[25468]: time="2016-04-21T08:33:25.890528192Z" level=error msg="Error running exec in container: attach failed with error: write tcp 10.99.0.99:2375->172.17.0.2:40968: write: broken pipe\n"
Apr 21 08:33:25 docker-host docker[25468]: time="2016-04-21T08:33:25.890563806Z" level=error msg="Handler for POST /exec/aca8b3206f70586afa35766edf858827b57dd1e7a5643878df1996c8c818f061/start returned error: attach failed with error: write tcp 10.99.0.99:2375->172.17.0.2:40968: write: broken pipe"
Apr 21 08:33:25 docker-host docker[25468]: 2016/04/21 08:33:25 http: response.WriteHeader on hijacked connection
Apr 21 08:33:25 docker-host docker[25468]: 2016/04/21 08:33:25 http: response.Write on hijacked connection

docker-php issue: https://github.com/docker-php/docker-php/issues/195

I'm getting same with 18.09.0 while stopping/starting 30 containers via docker-compose. But they writes summary ~100 messages per hour to stdout/stderr.