Until Ubisoft is patching up the latest bugs and glitches for Assassin’s Creed Unity, they gave us some advice about how to prevent the problem with the crash at the main menu. The source of the problem was discovered by Ubisoft, and it is confirmed that it occurs on all platforms when the player presses the continue button on the main menu.

Until the fixing patch will be released, Ubisoft recommends you to

• Do not add any IN-GAME RECENT PLAYER as a GAME CONTACT 
• If you already have GAME CONTACTS, perform the following to remove them: My Brotherhood > My Contacts > Game Contacts (using RB/R1) > Focus on a Contact (LS) > More Actions (Y/Triangle) > Remove from contacts.

Hope this will work for all of you that have big issues with the game and that you have enough patience to wait the third patch for Assassin’s Creed Unity, about which you can read right here.

Source: Ubisoft