Change a Raspberry Pi’s Wi‑Fi from the microSD card when it can’t join your network

# Why this matters

# Overview of the method

Raspberry Pi OS uses two partitions on the microSD card. The Wi‑Fi settings live in the rootfs partition. Recent OS releases use NetworkManager and store connection profiles as.nmconnection files. The process is: mount the rootfs partition on a Linux system, edit an existing.nmconnection file or create a new one with the new SSID and password, set the file's permissions so NetworkManager accepts it, flush writes with sync, unmount, then boot the Pi.

# What you need

• A Linux computer (or any machine that can mount ext4 rootfs) and an SD card reader.
• The Pi's microSD card.
• The new Wi‑Fi SSID and password.

# Steps (high level)

1. 1Power down the Pi and remove the microSD card.
2. 2Insert the card into a Linux machine and mount the rootfs partition.
3. 3Locate NetworkManager connection files (.nmconnection) in the rootfs.
4. 4Edit an existing profile or create a new.nmconnection file with the new network name and passphrase.
5. 5Set the connection file permissions so it is readable only by root (NetworkManager ignores files with permissive permissions).
6. 6Run sync before unmounting to ensure changes are written to the card.
7. 7Unmount, reinsert the card into the Pi, and power it on.

# Permission detail to watch

NetworkManager will ignore a connection file unless it is readable only by root. That means you must adjust the file permissions after editing on your Linux machine. If the file remains world‑readable, the Pi won't pick up your changes.

# Confirming the Pi connected

After booting the Pi with the updated connection file, check your router's device list for the Pi's new IP. If that's not available, scan the subnet with Angry IP Scanner or nmap to discover the address.

# When this helps

• The router's SSID or password changed and you can't or don't want to attach input/output to the Pi.
• You've moved the Pi to a different network and need to update credentials quickly.

# Additional tips

• Always run sync before unmounting the card so edits are not left in cache.
• Keep a backup copy of any original.nmconnection file before overwriting it in case you need to restore the prior settings.

# Where to read more