Authentication token manipulation error 🐧 Linux

passwd: Authentication token manipulation error

passwd couldn’t update the password — the root filesystem is read-only, /etc/shadow has wrong permissions/attributes, or a PAM rule rejected it.

Seen on: Linux

Meaning

Common in recovery mode (root mounted read-only), on systems where /etc/shadow was made immutable, or when the disk is full.

Common causes

  • Root filesystem mounted read-only (recovery/single-user mode)
  • /etc/shadow or /etc/passwd immutable (chattr +i) or wrong permissions
  • Disk full
  • PAM password policy/module failure

⚡ Quick fix

  1. Remount rw: mount -o remount,rw /
  2. Check lsattr /etc/shadow and permissions
  3. Free disk space

Detailed fix by platform

Linux

  1. bash
    mount -o remount,rw /
lsattr /etc/shadow /etc/passwd
ls -l /etc/shadow   # should be root:shadow 640 (Debian) or 000 (RHEL)
passwd username

How to diagnose

  1. Mount — ro or rw?
  2. Attributes — lsattr flags
  3. Disk — df -h /

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