Fairphone 4: v7.x builds blocked due to v6.x locked bootloader upgrade issue

Currently v7.x builds are not released to stable due to users upgrading from v6.x being left with an unbootable device if the bootloader is locked.

A user can manually upgrade to v7.x beta if they do a factory reset or if the device is not locked by using the FP4 beta build with the name iode-7.x-YYYYMMDD-FP4-ota-bricks-device-when-upgrade-from-v6-bootloader-relocked.zip from the iodéOS beta repository.

If a user with a locked bootloader fails to factory reset before applying the update and it is then left unbootable, they can either go to Recovery and perform the factory reset, or instead attempt to boot "about 6-7 times without success, after which the system will revert to the v6.x build and should boot thanks to the a/b partition scheme." After booting back to v6.x, they can save all their data, perform a factory reset, and once again attempt to manually update to the v7.x beta build.

As a further clarification, there should be no problem with having a locked bootloader with v7.x, it is just that if it was locked with v6.x then a factory reset it needed to move to v7.x.

At this point we can see if a possible future firmware update by Fairphone will resolve the issue, but otherwise we don't know of other ways forward.

If others find any LineageOS-based builds that can migrate from an Android 15 base to an Android 16 base when the bootloader is locked without performing a factory reset, please let us know.

Here is the thread discussing the issue where users can give feedback:

https://community.iode.tech/t/fp4-iode-7-status-issue-tracker/7653