Merge branch '1135-update-fp6-security-patch-date' into 'master'

install_e_file_name: install_e_official_lock_bootloader

ignore_troubleshooting_tips: true

troubleshooting_guide_url: https://forum.fairphone.com/t/guide-to-bootloader-and-bricking-2025/121352

requirements_file_name: requirements_FP6

requirements_file_name: requirements_rollback_specific

verified_boot:

- {vendor: 'Any vendor', supported: 'yes'}

bootloader_relocking:

{% include templates/requirements.md %}

{% include alerts/danger.html content="Your phone has a security feature called anti-rollback protection. This prevents installing older software versions once a newer one is installed.

If you try to install an older software version while your bootloader is locked, you may trigger an anti-rollback error and brick your device." %}

<details>

<summary>Tips on how to avoid bricking your device</summary>

<div style="margin: 20px 0;">

<p><strong>1. Find your device’s current rollback date (Security Patch Level)</strong></p>

<ul>

  <li>Go to Settings &gt; About Phone &gt; Android Version &gt; Android Security Patch Level.</li>

  <li>Note the full date (e.g., 2025-06-05). This is your current rollback date.</li>

</ul>

<p><strong>2. Understand how /e/OS sets its rollback date</strong></p>

<ul>

  <li>On most operating systems, the rollback date matches the Security Patch Level (SPL) exactly. On /e/OS, the rollback date is always set to the 5th day of the SPL’s month, regardless of the specific day in the SPL.</li>

</ul>

<p><strong>Examples:</strong></p>

<ul>

  <li>An /e/OS build with SPL 2025-06-05 has a rollback date of 2025-06-05.</li>

  <li>An /e/OS build with SPL 2025-07-01 has a rollback date of 2025-07-05.</li>

</ul>

<p><strong>3. Select a compatible /e/OS build</strong></p>

<ul>

  <li>You must choose an /e/OS build where its rollback date (the 5th of the SPL month) is equal to or newer than your device’s current SPL date from Step 1.</li>

  <li>You can find the SPL for each /e/OS build in the Downloads section.</li>

</ul>

<p><strong>Key points about anti-rollback behavior:</strong></p>

<ul>

  <li>The anti-rollback index increases whenever you install a newer build with a newer rollback date and a locked bootloader. It cannot be decreased.</li>

  <li>Protection depends only on the rollback date, not the Android version (e.g., Android 14 vs. 15).</li>

  <li>This restriction only applies when the bootloader is locked. It is ignored if the bootloader is unlocked.</li>

</ul>

<p><strong>Examples:</strong></p>

<ul>

  <li>Device SPL: 2025-06-05 | /e/OS SPL: 2025-05-01 (Rollback: 2025-05-05) → Will brick the device</li>

  <li>Device SPL: 2025-06-05 | /e/OS SPL: 2025-06-01 (Rollback: 2025-06-05) → Installation will succeed</li>

  <li>Device SPL: 2025-06-05 | /e/OS SPL: 2025-07-01 (Rollback: 2025-07-05) → Installation will succeed</li>

</ul>

<p><strong>Before installing, always verify that the /e/OS rollback date (the 5th of its SPL month) is greater than or equal to your device’s current Security Patch Level.</strong></p>

</div>

</details>