Bugs in NetHack 4

Like other NetHack variants, NetHack 4 has bugs. This page tracks the status of the Bugs in NetHack 3.4.3 in NetHack 4, together with new bugs introduced in NetHack 4.

Special thanks to Jonadab the Unsightly One for helping to compile this list.

NetHack 4's developers would appreciate feedback on these bugs, especially the ones marked as "Unclear" (if anyone knows what these bug reports mean, please let us know!), and the ones marked as "Unknown" (where typically nobody knows what to do to reproduce the bug).

Key:

• Fixed: The bug existed in NetHack 4 (or one of its predecessor variants, AceHack or NitroHack) and was fixed.
• Incidentally fixed: The bug was fixed due to unrelated changes made in NetHack 4.
• Fix available: The bug has a fix available for it in some other variant, but that fix has not yet been merged into NetHack 4.
• Confirmed: The bug has been reproduced in NetHack 4 (typically with a save file recorded for it).
• Moot: The bug's context no longer exists in NetHack 4.
• Info available: The cause of the bug has been explained for NetHack 3.4.3 on this wiki, and thus further investigation was not worthwhile.
• Debatable: There is some doubt as to whether this is a bug, or about whether it would be reasonable to fix it.
• Unclear: It is not clear what the bug description refers to.
• Unknown: The bug has not been reproduced in NetHack 4, but may well still exist.

Number	Status	Description (3.4.3)	Additional notes
C341-1	Moot	Monsters affected by stinking cloud always get angry at the hero even if the hero did not create the cloud.	This only affects bones files made on NetHack 3.4.0, which are not compatible with NetHack 4.
C341-4	Incidentally fixed	opthelp does not list use_inverse
C341-5	Unknown	When you see your pet move, the pet may be referred to as "it".
C341-7	Fixed	Skilled or expert caster of fireball/cone of cold can't target a monster known only by infravision or ESP.	Fixed by Grunt.
C341-10	Debatable	Fruit names ending in "us" are incorrectly considered plural.
C341-18	Fixed	ki-rins and couatls can wear (and may have) armor.	Shields, boots, gloves, and (non-metallic for ki-rin) helmets. Fixed by Grunt.
C342-12	Unclear	There are a number of places that misuse "your".
C342-13	Unknown	Hangup can cause loss of objects being moved internally.
C342-16	Fix available	If you self-genocide while polymorphed, the death message makes no sense.	"You return to [racial] form. DYWYPI?" GruntHack changes this to "As you return to [racial] form, you die."
C342-19	Confirmed	Things that can kill you in the future (like stoning) can cause messages to show up out of order.	"You are a statue. Your skin begins to peel away."
C342-22	Fix available	Monsters can hide under cockatrice corpses without getting stoned. GruntHack contains a fix for this.
C343-31	Unknown	You can get a message telling you a monster wields a weapon it already was wielding.
C342-36	Incidentally fixed	If unable to see yourself while invisible and you are bestowed a spellbook, it doesn't show up on the display.	Seems to have been fixed by NitroHack's changes to the display engine.
C342-46	Fix available	Cleric cast lightning doesn't blind as other lightning does.	Refers to the monster cleric spell, CLC_LIGHTNING. GruntHack fixes this.
C342-50	Confirmed	If you're hiding on the ceiling and try to #sit, you automatically unhide.	#sit, #monster, #sit: "You sit on the helm of brilliance. It's not very comfortable... You are already hiding."
C342-51	Fixed	The game thinks trappers hide on the ceiling.	In D&D, they apparently hide on the floor. Turns up in two known places: dislodging a trapper with a drum of earthquake, and ambushing a monster while in trapper form. Fixed by Grunt.
C342-54	Confirmed	Statues of unique monsters in bones files are not handled correctly.	If the unique monster in question doesn't normally spawn on that level, and was rather brought there from some other level (in the other game), zapping stone to flesh at it causes a segfault.
C343-1	Unclear	At a pit the game can give messages with poor grammar.
C343-2	Fixed	Wielded silver arrows don't cause silver damage on some silver-haters.	Fixed by Alex Smith.
C343-3	Unknown	In the ranger quest, monsters can end up off the map to the left.
C343-4	Confirmed	On the Rogue level, tunnelling through rock doesn't leave a passage.	Refers to tunneling monsters, like umber hulks, rather than a player with a pickaxe.
C343-5	Fixed	In wizard mode, level teleport in the endgame can cause a crash if confused.	Fixed by Grunt.
C343-6	Fix available	You can #sit on an object at the bottom of a pit that you are not in.	Fixed in AceHack and GruntHack.
C343-7	Fixed	When a steed pushes a boulder into a pool, the message misuses "you".	Fixed by Alex Smith.
C343-8	Fixed	Plural of Nazgul is Nazgul - not Nazguls	Fixed by Patric Mueller.
C343-9	Fix available	Trap messages referring to a named steed when hallucinating are poorly worded.	If riding at the time, e.g. "You lead poor fire giant into a pit!". Fixed in GruntHack, though by a more complicated means than necessary for vanilla / NH4.
C343-10	Fix available	If there is a corpse in a pit, you have to enter the pit to pick it up but not to eat it. Fixed in GruntHack.
C343-11	Moot	If you ask for help ('?') at a "what direction" prompt, you don't get to enter a direction afterward if the cmdassist option is set.	cmdassist no longer exists.
C343-12	Fixed	You can't use '>' to enter a pit.	Fixed by Patric Mueller.
C343-13	Unknown	On polymorph, you can get the message "It turns into it".	According to Grunt, this happens in vanilla if an invisible purple worm swallows a shapechanger. Has not been tested in NetHack 4.
C343-14	Fix available	The initial and any tombstone message resulting from eating an identified artifact is gramatically incorrect.	Requires choking on a formally IDed artifact.	Fixed in GruntHack.
C343-15	Fixed	You can get a message that an invisible monster looks much better.	Fixed by Alex Smith.
C343-16	Fix available	Player polymorphed as a xorn can't pick up items in pits.	Fixed in GruntHack.
C343-17	Fix available	After polymorphing into a xorn and returning to human form, player can be stuck in a pit that isn't there.	Fixed in GruntHack.
C343-18	Fixed	Scaring a mimicing mimic gives an incorrect "turns to flee" message.	Fixed by Alex Smith.
C343-19	Fix available	Dipping acid in a fountain may not destroy the acid.	Seems inconsistent about whether it's destroyed or not, despite exploding. Fixed on NAO and GruntHack.
C343-20	Info available	When dying immediately on entering a level, the map may show you dying on the previous level.
C343-21	Confirmed	Pets can be pulled through closed doors with a leash.
C343-22	Fix available	You can untrap a monster in a pit while levitating.	Fixed in GruntHack.
C343-23	Unknown	Dungeon collapses after vault guard fails to lead you out.
C343-24	Moot	Documented default for option "null" is "off"; default is actually "on".	The rendering no longer works like that anyway.
C343-25	Fix available	You can trip over a cockatrice corpse safely.	Wear gauntlets of fumbling and walk around among cockatrice corpses. "You see here a cockatrice corpse. You trip over it. You make a lot of noise!" Fixed in GruntHack, where tripping is unsafe if not wearing boots.
C343-26	Fix available	A frozen swamp may be called a moat.	Go to Jubilex' Swamp and start zapping around with a wand of cold. "The moat is bridged with ice! You hear a cracking sound." Fixed, along with several related misuses of "moat", in GruntHack by greater use of waterbody_name.
C343-27	Unknown	Kicked objects do not slide properly on air or water levels.
C343-28	Unclear	There are several places that can't tell the difference between a "hat" and a "helmet."
C343-29	Fix available	When taking things out of a bag of holding, messages may say "lifting" instead of "removing."	This happens when you get the confirmation asking if you want to continue (because your encumbrance level would increase and you are over your threshold). Fixed in GruntHack.
C343-30	Fixed	Cursed scroll of destroy armor on cursed armor doesn't always interact correctly.	Alex Smith
C343-31	Debatable / Fix available	If you hit a cockatrice with a weapon that breaks, you can be stoned.	Reproduced by wielding a boomerang in melee combat with negative luck. Fixed in GruntHack.
C343-32	Confirmed	When blind and levitating, the hero can still discover stairs.	Use the go down command. "You are floating high above the stairs."
C343-33	Unknown	Sometimes a monster may remain hidden under a corpse that has rotted away.
C343-34	Confirmed	Mimics on the rogue level may try to mimic a closed door.	Mimic may need to be located in a doorway.
C343-35	Info available	Polymorphed or shapechanged monsters may get the wrong number of hit points.
C343-36	Info available	Weight of corpses on special levels may not be calculated correctly.	This also goes for statues, e.g. the Oracle centaur statues.
C343-37	Confirmed	Mimics may mimic a boulder over a pit or hole.	Also "a statue of a (monster) on a pit on the floor of the room" or "a pit on a stairway up".
C343-38	Info available	Dismounting and kicking a monster that jumps may result in landing on the wrong side of a wall.	In very confined spaces, mnexto() may not be able to find a space next to you.
C343-39	Incidentally fixed	Restoring a game where the character is wielding Sting may result in temporary display errors during the restore process.	Cannot reproduce in NH4, probably due to the Nitrohack UI changes.
C343-40	Info available.	Monster thrusting one of multiple wielded daggers gives misleading message.
C343-41	Confirmed	A rolling boulder falling into a pit you can't see only makes a sound if the hero is blind (or blindfolded).	If you only can't see it happen because it's dark, you get no sound.
C343-42	Confirmed	If a fire trap melts ice, it may trigger twice in the same turn.	Reproduced via polyself into a red dragon.
C343-43	Incidentally fixed	An invisible troll that revives may be shown until it moves.	Cannot reproduce in NH4, probably due to the Nitrohack UI changes.
C343-44	Info available	Shopkeepers, doors, and traps interact oddly.	For example, if you break a wand of digging on the entrance square, the shopkeeper will usually remove only some of the pits.
C343-45	Unknown	Dropping the corpse of a unique monster without a personal name down the stairs gives a badly formed response.	"You drop the Oracle's corpse. The corpse falls down the stairs. Your movements are unencumbered." However, when the hero descended the stairs, no corpse was present. This may possibly refer to monsters with a personal name: "You drop Medusa's corpse. Corpse falls down the stairs."

to be continued…