The reset app bugs are a series of computing errors in Final Fantasy Brave Exvius, which occur when soft resetting or crashing the game, resulting in its closure then the player reopens it. These are the known lists of known occurrences, some of which have been fixed as of later updates. It is not fully known whether these were unintended bugs, deliberate, or just a side effect let slide but fixed due to balancing concerns.
Turn count reset
The error reset turn counts for predetermined patterns. Given several bosses rely on turn counts to apply certain attacks (i.e. some performed once every three turns or once every four turns), this error meant these attacks could never be used, as all the player had to do was soft reset the app and the boss's turn count would be reset.
In the Global version an update included a turn count for the battle, found in the upper right section of the screen. While the boss's turn count was reset, the "battle's turn count" did not. This resulted in strange phenomena in which bosses would behave like if it was the first turn, while it could be the 10th or 20th turn.
Because the Battle Turn Count was unaffected, some turn based consequences were unaltered, for example, some bosses stopped dropping Limit Burst Crysts after a certain amount of turns, which remained true no matter how many times the player reset the app.
The most famous examples were found in The Rumble of Malboro Trial, where many players exploited the reset app to avoid the perilous attacks like Devour, Berserk Touch, Tentacles Blow and Tentacles Rampage. The lesser Malboros would stop dropping crysts after 20 turns of being summoned, but would start dropping them if resummoned which reset their counter.
This problem has been fixed.
Known as the RNG bug, this programing error caused certain outcomes to change depending on the attacks involved. At its most basic, this error changed (if used during enemy party turn) the target of their attacks. Players could use this exploit to avoid certain units from being killed and having the damage (mostly from single target attacks) to be spread more evenly and ensure favorable outcomes.
There were some outcomes based on luck that were affected, for example if in a certain turn or threshold a boss attack made it choose between attacks A, B or C, the player could soft reset the app to have the boss use the attack that better suited it.
Certain luck-based abilities were unaffected. Setzer's fixed damage abilities rely on luck, but the damage they deal per turn is predetermined, so no matter how much the player soft reset the app, the result would never change.
Soft resetting the app is a common technique when a player screws up a turn, a chain or some other move. Doing so during the player's turn will reset the player's turn as if starting it.
The most famous uses of this bug were during the Wicked Moon and The Fallen Ice Bird Trials. In the former, the Boss Bloody Moon has a threshold attack whose outcome is luck-based from a checklist in priority order, and players could soft reset the app to get the least dangerous result. For the latter, the Trial is infamously known as the "Soft Reset Trial" because of a nasty preemptive strike that is potentially deadly for the player's units. As a result, players soft reset to survive on the best conditions and subsequently defeat the boss.
This bug has been fixed. The player can still soft reset the app if they committed a mistake they wish to fix during their turn.
A more recent form of the bug, which has both beneficial and potentially imperious effects, involves the player soft resetting the app (reportedly twice) during a battle (although it can happen in less than that). The player's units will appear as if the player used Lapis to continue from a Game Over, namely, they will be with full HP/MP, have their Limit Burst gauges filled, the Esper Gauge filled, status ailments/buffs/debuffs removed, etc.
The game doesn't treat this as a continue, so the player won't fail missions related to no continues. The player doesn't lose any mission achieved (i.e. if a mission demands using Magic Damage three times, and this condition was fulfilled, it remains fulfilled). Whatever HP the enemies have remains.
There are some problematic effects that happen nonetheless, for example, characters with build up damage—like users of Ja-tier spells—will find their stacks gone. If they had built damage, they must start from scratch in piling their power up. If the player switches devices when this occurs, the battle may be forfeited. Setup abilities (those that unlock other abilities) are also reset.
Some effects are not fully clear, like an enemy's buffs, debuffs, or other unexplored effects. Some people also report actually losing Lapis (100) when this happens, as if performing a continue.
As of Feb 8th, 2018, this bug has been fixed.