There are good bugs, bad bugs, and ugly bugs. Even the Ultima series wasn't bug-proof, resulting in some serious bugs that in the worst case can ruin all progress. All currently known bugs are listed here. Note that bugs that can be exploited for cheating are not listed here.
The list is not complete, further bugs will be added over time.
- A problem that is common to several versions of the game is that the numbers for stats and hitpoints can "roll over", meaning that, when increased beyond the maximum of 99 or 9999, they fall back to zero. It is a well known weakness of the game and even Richard Garriott himself knew about it and therefore made Lord British give out fewer hitpoints per tribute payment the higher they already are, so that the danger of rolling over is lower. Thankfully the Ultima II Upgrade Patch fixes that.
- A bug in the original Apple II version prevents the player from ever increasing the "strength" attribute in-game (i.e. after the character creation process). In case not enough points were allocated to "strength" in the first place, this can prevent him or her from wearing the types of armor that are needed for protection during space flight, making the game unwinnable.
- Another nasty bug is the "Divide by Zero" error that occurs in the PC version when it is run on any PC significantly faster than an original 1980s machine. Ultima II isn't made for fast computers and crashes without further comment. Thankfully, the patch mentioned above fixes this as well.
- Not a real bug, but still game-breaking. Due to sloppy conversion, the later releases of the PC version of Ultima II that came in CD compilations got broken. The game was originally sold on three floppies, during a time when DOS didn't yet know sub-directories. Some files on different floppies had the same names but different content. When it was all put into one directory for the compilations, most planet maps from the galactic disk got overwritten by various Earth maps, so that the inner planets now look exactly like Earth's various time periods (since the inner planets do not contain any vital items or clues in this game, this didn't make the game unwinnable, merely very odd). The patch mentioned above fixes this as well.
- The are several conversation bugs in the TLK-files making certain conversations impossible to reach.
- The "Open" spell doesn't work. While manually opening a chest gives the player a fair chance to evade a possible trap, the spell actually rises the chance of a trap to hit to 100%!
- The correct way to exit the balloon is to land it first, then exit it. The Apple version, however, had a bug that allowed you to exit the balloon while it was still in flight. This put the party into a confused mode. This mode was mostly like that of being on the surface, with the notable exception of non-occultation, and NPCs and monsters behaved as though the party was in flight.
- A very annoying bug is included with the virtue of Valor. If the player character already has 9999 experience points, they should not lose the eighth of Valor. This is because the game stops giving the player valor points when the experience maximum is reached, making the game unwinnable should the eighth of Valor be lost at that point.
- A really bad bug appears in combination with dead party members. If a companion dies and the party then is filled to the maximum of eight, resurrecting the character will turn the companion in question into a zombie that won't leave you alone. Since the party can only be 8 strong, have a 9th member screws up the game until it crashes.
- Some quest-related items like the vortex cube can disappear when placed on the ground after saving and loading.
- The disk version of the game had a bug in the lower levels, known as the "inventory bug". Essentially it would strike at random when changing levels, screwing up the inventory which generally resulted in loss of vital items. The CD-version fixes this bug, but it strangely re-appears in the PSX-Port.
- A very nasty bug can happen in the sequence where the Avatar has to kill a Tyrannosaurus with a boulder. If the bug happens, a random party member will be frozen forever.
- Another bug happens after uniting the tribes. Leaving the Myrmidex caves after having beaten the Great Drum, results in the player being stuck in an infinite, self-repeating grassland.
- Items that are left in a location, such as a village hut, can dissapear. Note this is particularly important for quest-related items. Confirmed disappearing items include the fire extinguisher, bucket, and jugs of platcha, as well as easily replaceable items like sabretooth tiger skins, bamboo flintlock rifles, and bows and arrows. While it is unclear whether this is caused by a proper bug or quick-fingered natives, in order to avoid restarting to complete quests it's a good idea to keep all unique items with the party.
- On the Great Mesa, where you are supposed to use a Giant Crystal on a stone socket, you can instead use the Crystal Brain, obtaining the same effect. You cannot retrieve the Crystal Brain from the socket, and it will disappear if you leave the area - but you can still finish the game without it. If you later use the Giant Crystal, it will be cast on the socket, but you won't see the cutscene again.
- A bug in the disk version of the game was that keys tended to simply disappear, making the game un-winnable. Origin thankfully fixed this problem with the CD-version.
- Flying with the Magic Carpet to Minoc has the strange effect of the murder site being cleaned up immediately. This makes the Serpentine Dagger vanish, thus it becomes impossible to confront De Snel. - The only workaround is using another Serpentine Dagger, since another bug is, that they are all the same.
- Another bug with the carpet appears when flying over the Isle of the Avatar. Unlike other sliding doors, one in the dungeon below is badly programmed and closes even if flying over the mountains under which it is. This makes the final dungeon un-winnable.
- Due to a bug, it is impossible to get Rankin to talk the truth with the cube. Thankfully this was fixed with an Exult mod.
- Trying to read the Golem-ritual scroll after having left the Test of Love results in a crash.
- A bug in the German version: some conversation topics do nothing when clicked on, as it seems their triggers are missing.
- It is possible to kill Cador in a bar fight, and then tell Yvella about where Catherine goes at noon. This creates the interesting situation where Cador lynches Lap-Lem despite already being dead.
Ultima Underworld II
- Being nasty to Nanna results in a bug that creates a never-ending servant strike, essentially becoming a plot-stopper since events in the game proceed with plot development. Fixed in the CD-version.
- Getting the Horn of Praecor Loth by destroying Praecor Loth results in a bug where the endgame (the appearance of Mors Gotha in the castle) can't be triggered.
- There is another bug which can cause the endgame to not trigger. The Djinn Bottle has to be placed in the center of the pentagram before breaking it. While it seems to work when putting the bottle near the edge, it actually doesn't. Can only be solved by getting the replacement bottle from the Void and doing it correctly.
- All of the ghosts in the game are the Chaos Hierophant. Talking to him before the right time is there will result in plot-stoppers.
- Also, the pillars in Isstanar's room teleport accidently to the test of purity, also resulting in plot-stoppers.
- One bug in Monitor can make the pikeman at the List Field, who manages the training, disappear. The cause is said bug, which lies in the banquet scene. The bug lies in the handling of internal game eggs (triggers). The usecode deletes the nearest egg trigger to the Avatar when opening the door to enter the banquet, which can erroneously be the Pikeman spawn egg for the List Field if you are to the west of the Banquet Hall. To avoid this, approach the banquet from the east.
- Stats-enhancing items like the Belt of Strength from Silver Seed, when Avatar is stripped off items (for example by taking a quest like the Maze) will not subtract their enhancement when taken away, but will internally store a restoration value (for example when avatar had strength 22 before equipping the Belt of Strength, and 30 (max value) afterwards, the Belt now has stored "take away 8 strength points when removing manually", and giving it to another party member will so not increase their strength by 10 but merely reduce it by 8 when it is taken away again from them). this can be used for cheating, to avoid the bug it's necessary to equip the avatar with the items after return from the scripted plot. exult bug report
- Beren's dialogue, when reaching the lava river after cooling it partly off, is buggy. Most of his lines vanish. The cause are flag problems. This can be avoided by either never talking to him, or angering him in Tenebrae and denying an apology.
- There is a book entitled 'Resurrection' on the first floor of the Monastery at the ArgentRock isle, the text of which is on the 'Intervention'. (usecode bug)
- Gwillim's dialogue is buggy. Once the dialogue is ended, there's no other option but 'Farewell', except for the Ghost Plot. (usecode bug)