If it’s a new Librem 5 with little to no use, reflashing PureOS with Crimson is recommended: Reflashing PureOS - Purism user documentation. Be sure to follow the tip admonition to add --dist crimson so that you run ./scripts/librem5-flash-image --stable --dist crimson.
Performing a system upgrade by updating the /etc/apt/sources.list file carries a lot of risk. You can’t let the phone lock itself (idle lock), otherwise you will need to work around it as the input method breaks.
Here is what I did for my Librem 5 to upgrade to Crimson without reflashing:
- Connect your Librem 5 to power.
- Change the screen blanking setting to “Never”. The lockscreen may become unusable partway through the upgrade so stopping the screen from turning off and automatically locking works around this known issue.
- Open the Settings app.
- Proceed to the Power menu.
- Change the Screen Blank option to “Never”.
- Open the Terminal app.
- Enter
sudo nano /etc/apt/sources.list. - Replace all occurrences of
byzantiumwithcrimson. - Press the Ctrl + x key combination and then press y to save and exit.
- While still in the Terminal app, enter
sudo apt updateand thensudo apt full-upgrade. Enter your password if it prompts you for it and then press y to confirm the updates. - Let the system upgrade itself, which may take upwards of 30 minutes and may prompt you during the upgrade.
- Once the upgrade has finished, restart your Librem 5. If you are unable to access the power menu, hold the power button for about 20 seconds to force it to power off and then power it on again.
- Once PureOS has loaded and you have logged in, open the Settings app and tap the Power menu again. Change the Screen Blank option to the previous setting.