Learn more about the maths in [The Intercept: Passphrases That You Can Memorize — But That Even the NSA Can’t Guess](https://theintercept.com/2015/03/26/passphrases-can-memorize-attackers-cant-guess/).
[[!img failure-to-activate.png link="no" alt="Welcome Screen with error message: Failed to activate some features of the Persistent Storage: Persistent Folder."]]
After starting Tails, the feature that failed to activate is marked as such in the Persistent Storage settings. You can try turning the feature off and on again or deleting its data to reset it entirely.
