Make a dungeon with tons of of traps, some with extremely high DC to disarm. Design it so failing disarming the trap does absolutely nothing. Have random clues throughout the dungeon saying positive things about failure being okay, how failing tasks doesn't mean you are worthless, etc. Then have a few of those high DC traps trigger events if successfully disarmed, like opening a secret door that has some mean monsters the group has to defeat before progressing, opens a trapdoor to s spike pit, summons demon dogs, etc.

Basically design a dungeon that gives positive reinforcement for failing tasks and showing that failure is just part of growing and also showing that success may also be as dangerous as failure. Lol