Key to the Past

Key to the Past is a main quest in Fallout 76.

Quick walkthrough
Acquire the following holodisk key fragments from various places across Appalachia:
 * Blackwater Bandits key fragment
 * Trappers key fragment
 * Diehards key fragment
 * Gourmands' key fragment
 * Cutthroats key fragment

Return to Rose so that she can produce a "master key" from those key fragments. Then go to the basement of the Pleasant Valley Ski Resort to find a raider cache storeroom with various loot.

Bugs

 * When leaving the world mid quest, some or all of the key pieces may be gone from inventory upon logging back in, forcing the player to repeat the respective quest stages to acquire them again and being able to continue the quest. There is no known fix other than to finish the whole quest during one session to avoid triggering the bug.
 * The bug seems to be triggered most often as a result of the game being closed abruptly - by crashing, task killing or using the ALT-F4 key shortcut. Avoiding those actions when possible and leaving the game world before quitting the game might help to prevent the bug from happening.
 * On the portion of the quest where the player character is asked to kill David, there will sometimes not be a tracking dot showing where Big Fred's BBQ Shack is.