What happened?

Description

When flashing an OS using Raspberry Pi Imager with custom configuration (hostname, SSH, Wi-Fi, locale, etc.) applied via the OS Customisation menu, the settings are intermittently not applied on first boot. The Pi boots with default/unconfigured settings as if the customisation was never written.

This issue is not consistent — it happens sporadically, making it harder to reproduce reliably.

Steps to Reproduce

1. Open Raspberry Pi Imager (latest version)
2. Select an OS (see tested list below)
3. Select target storage device
4. Open OS Customisation settings and configure (hostname, SSH enabled, Wi-Fi credentials, locale, etc.)
5. Flash the image
6. Insert the SD card into the Raspberry Pi and boot
7. Expected: Custom configuration is applied on first boot
8. Actual: Configuration is sometimes ignored — default settings are used instead

Environment

Tested OS Images

• Raspberry Pi OS Lite (64-bit)
• DietPi
• Armbian
• Ubuntu (latest version available in rpi-imager)

The issue occurs across all tested images, on both host OSes (Windows 11 & Nobara Linux).

Additional Context

• The custom configuration files (firstrun.sh / user-data in the boot partition) may not be written correctly or may not be read/executed on boot.
• Since the issue is intermittent, it could be related to a race condition during the write/verify phase, or the files not being flushed to disk properly before eject.

Version

2.0.6 (Default)

What host operating system were you using?

Windows

Host OS Version

25H2, Nobara Linux 43 KDE — Kernel 6.19.2-200.nobara.fc43.x86_64

Selected OS

Raspberry Pi OS 64bit lite, DietPi, Armbian, Ubuntu

Which Raspberry Pi Device are you using?

Raspberry Pi 5, 500, and Compute Modules 5

What kind of storage device are you using?

microSD Card in a USB reader

OS Customisation

• Yes, I was using OS Customisation when the bug occurred.

Relevant log output