(answered) Install /e/ on FP5 with newer Security Patches

/e/OS Devices Fairphone
2

Perhaps it helps to quote the full advice from the install page, Install /e/OS on a Fairphone FP5 - “FP5”

Caution: The FP5 comes with an anti-rollback feature. Google Android anti-roll back feature is supposedly a way to ensure you are running the latest software version, including the latest security patches.

If you try installing a version of /e/OS based on a security patch that is older than the one on your device, you will brick your device. Click on Details below for detailed information
To check the security patch level on your phone with a locked bootloader, prior to installing /e/OS, open your phone Settings » About Phone » Android Version » Android Security Patch Level.Then compare it against the level of the security patch on the /e/OS build as visible in the Downloads for FP5 section below.

The following values control whether anti-rollback features are triggered on FP5:

  • Rollback protection errors trigger if you install an update whose version number is LESS than the rollback index’s value stored on device.
  • The value of rollback index is UPDATED to match ro.build.version.security_patch’s value of the currently installed version, but only if the bootloader is LOCKED.
  • The value of rollback index is NOT dependent on the currently installed ANDROID VERSION.
  • The value of rollback index can NEVER be DOWNGRADED.
  • Rollback protection errors are FATAL when the bootloader is LOCKED.
  • Rollback protection errors are IGNORED when the bootloader is UNLOCKED.

Here are some examples to help you understand how anti-rollback features work:

Example 1

  • Your FP5 with Google Android has a Security Patch Level saying June 5, 2022
  • The /e/OS build available says: /e/OS build : R official (Security patch: 2022-05-05)
  • In this example, the /e/OS build has an older Security Patch level than the origin, so the anti-roll back protection will trigger, and you will brick your phone

Example 2

  • Your FP5 with Google Android has a Security Patch Level saying June 5, 2022.
  • The /e/OS build available says: /e/OS build : R official (Security patch: 2022-06-05)
  • In this example, the /e/OS build has the same Security Patch level than the origin, so the anti-roll back protection will pass, and you will be able to install /e/OS with no issues.

Example 3

  • Your FP5 runs Google Android -R while /e/OS is now available based on AOSP -S.
  • Your FP5 with Google Android has a Security Patch Level saying 2022-10-03 or October 3rd, 2022.
  • The /e/OS build available says: /e/OS build : S official (Security patch: 2022-06-05)
  • In this example, the /e/OS build has an older Security Patch level than the origin, so the anti-roll back protection will trigger, even if the /e/OS version runs on a more recent version of AOSP. In this example, you will brick your phone.

/quote.

The instructions tell us to unlock the bootloader in order to allow to install /e/OS.

The real danger is expressed

Rollback protection errors are FATAL when the bootloader is LOCKED.
Rollback protection errors are IGNORED when the bootloader is UNLOCKED.

Rollback protection errors + user locks the Bootloader; the phone is bricked.

Rollback protection errors + user does not relock the Bootloader; the error is ignored.

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