EROFS (errno 30)

errno 30

LINUX

Read-only file system

Also searched as: Read-only file system, errno 30, EROFS: read-only file system

Linux terminal running strace with the failing system call and errno highlighted
Linux errno: trace the exact failing system call before changing anything.

What it means

EROFS, 'Read-only file system' (errno 30), means a write was attempted on a filesystem mounted read-only. Linux often remounts a filesystem read-only automatically after detecting errors, so a sudden EROFS on a normally writable disk deserves investigation.

Applies to: Linux, macOS (BSD errno), WSL, Docker containers

How to fix EROFS (errno 30)

  1. Check how it is mounted with 'findmnt <path>' or 'mount | grep " ro"'
  2. Look at 'dmesg -T' for messages like 'Remounting filesystem read-only' that indicate disk or filesystem errors
  3. Back up data, then run 'fsck' on the unmounted filesystem (from a rescue system for the root filesystem)
  4. If the read-only mount was intended, remount it read-write with 'sudo mount -o remount,rw <mountpoint>'
  5. In Docker or Kubernetes, check whether the container uses '--read-only' or 'readOnlyRootFilesystem' and write to a mounted volume or tmpfs instead
  6. On macOS, the system volume is read-only by design; write to your home or /usr/local instead

Why it happens

Filesystems are read-only by mount option, by policy (containers, immutable OS images, macOS system volume), or after the kernel detects corruption or I/O errors and protects the data by remounting read-only.

FAQ

Why did my Linux disk suddenly become read-only?

The kernel likely found filesystem or disk errors and remounted it to prevent damage. Check dmesg and SMART data before forcing it writable.

Related errors

ENOSPC (errno 28)EPIPE (errno 32)EMFILE (errno 24)EADDRINUSE (errno 98)ECONNRESET (errno 104)ETIMEDOUT (errno 110)ECONNREFUSED (errno 111)EHOSTUNREACH (errno 113)

Source: Linux kernel errno.h · fixes written and reviewed by the editors (see our editorial policy)

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