Switch on the computer and iImmediately press-and-hold the <span class="keycap">Option</span> key (<span class="keycap">Alt</span> key) until a list of possible startup disks appears⌥</span> or <span class="keycap">Alt</span> key) when the startup sound is played.
Immediately press-and-hold the <span class="keycap">Option</span> key (<span class="keycap">⌥</span> or <span class="keycap">Alt</span> key) when the startup sound is played.
Hold the key pressed until a list of possible startup disks appears.
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Turn on your Mac, then press and hold <strong>Command(⌘)+R</strong> immediately after you see the Apple logo. Your Mac starts up from <a href="https://support.apple.com/kb/HT201314">macOS Recovery</a>.
Turn on your Mac, then press and hold <strong>Command(⌘)+R</strong> immediately after you see the Apple logo. Your Mac starts up from <a href="https://support.apple.com/kb/HT201314">macOS Recovery</a>.
25
When you see the macOS <em>Utilities</em> window, choose <strong>Utilities ▸ Startup Security Utility</strong> from the menu bar.
When you see the macOS <em>Utilities</em> window, choose <strong>Utilities ▸ Startup Security Utility</strong> from the menu bar.
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[[!img install/inc/screenshots/grub.png link="noclass="screenshot" alt="Black screen ('GNU GRUB') with Tails logo and 23 options: 'Tails' and 'Tails (Troubleshooting Mode)' and 'Tails (External Hard Disk)'."]]
[[!img install/inc/screenshots/grub.png class="screenshot" alt="Black screen ('GNU GRUB') with Tails logo and 3 options: 'Tails' and 'Tails (Troubleshooting Mode)' and 'Tails (External Hard Disk)'."]]
The <b>Troubleshooting Mode</b> entry disables some features of the Linux kernel and might work better on some computers. You can try this option if you think you are experiencing hardware compatibility errors while starting Tails.
The <b>External Hard Disk</b> entry makes it possible to [[start from an external hard disk|doc/advanced_topics/external_hard_disk]] and some [[problematic USB sticks|support/known_issues#problematic-usb-stick]].
