error while creating mount source path "/host/data": mkdir /host/data URIs read-only file system

TL;DR: Docker tried to auto-create the bind source and the filesystem refused. Create the directory yourself somewhere writable (mkdir -p), or remount the filesystem read-write if it should be writable. Common triggers: paths under /usr or /System on locked-down hosts, and containers with read-only root filesystems.

The error

error while creating mount source path "/host/data": mkdir /host/data URIs read-only file system

Fix it

1. Check the filesystem state:

mount | grep " /host " Expected: shows ro if read-only.

1. If it should be writable, remount:

sudo mount -o remount,rw /host Expected: no output; mount | grep now shows rw.

1. Or simply use a writable location:

mkdir -p [HOME]/... and bind that instead.

1. Re-run the container.

When this applies

• Bind sources under read-only mounts (live USB, kiosks, hardened hosts)
• macOS /System paths via Docker Desktop (SIP-protected)

When this does NOT apply

• SELinux "permission denied" on existing dirs (label problem, separate skill)
• "bind source path does not exist" on a writable fs (just mkdir)

Versions

All Docker versions.

Why it happens

The -v shorthand auto-creates missing source directories via mkdir. On a read-only filesystem the mkdir fails and docker surfaces the raw error instead of proceeding.

Edge cases

• Switch to --mount, which fails fast with 'bind source path does not exist' instead of attempting mkdir; clearer for scripts.
• On Docker Desktop Mac, the VM's filesystem layout differs from the Mac's; keep binds under /Users (shared by default).
• Read-only rootfs containers (--read-only) are unrelated; that flag affects the container, not the host source path.