Slot Machine Malfunctions

When players don't get the jackpot money they expected

Last update: January 24, 2024


Play this slot machine with play money or real money at Bovada

Gold Rush Gus slot machine

No popups, no download, no registration, no B.S., just the game. One click and you're in.

Like all machines, slot machines occasionally malfunction.  Sometimes such a screwup makes the player think she's won a huge jackpot, which feels like a gut-punch when she learns she didn't actually win.

There are three types of malfunctions that make players think they won: 

  1. Display errors.  A video slot shows a huge number of credits won, even though the player didn't land the jackpot symbols on the payline.
  2. Setting errors.  The player lines up a winning combo, but the machine is set to the wrong jackpot amount.
  3. Mechanical errors.  With electromechanical slots (with physical reels), the reels can accidenatally land on a winning combo even though that's not what the computer actually chose.

There are many examples of each  And lucky for you, I've summarized them for you below.  (If you know of a case that's not listed, please let me know.) 

When a slot malfunctions, players don't get—and don't deserve—the big payout.  If a blackjack dealer accidentally said you won $5000 when you actually won only $500, you wouldn't insist that you won just because the dealer misspoke.  You wouldn't jump up and down screaming, "But you said!  You said!  I'm gonna sue!"  You wouldn't do that unless you were a complete idiot.  But as soon as a machine makes the same kind of error, misstating that a player won when she obviously didn't, then players can't wait to reveal that they have absolutely no clue.

A display error on a slot machine is just the machine version of a dealer misstating the payout.

On the other hand, it's certainly heartbreaking to be denied a large jackpot, and it's entirely appropriate for players to press the casino for meaningful ompensation for the bad experience they had.  However, to be clear, the real culprit is the slot machine manufacturer, not the casino.  The casino didn't make the machine, and they're as much a victim as the player:  They bought or rented a machine, it didn't work properly, and now they not only have an unhappy customer, but that customer is also probably suing them.  The solution is to require slot makers to compensate players when a malfunction makes them think they won (say, $50,000).  That would ensure that players get a decent amount of compensation for their bad experience, the innocent casinos would be off the hook, and slot makers would have an incentive to make sure their machines don't screw up. (A nod to Mission146 at the WizardOfVegas forum for pointing out this remedy.) 

Payout display errors

Sometimes slot machines show an impossibly large number of credits won.  And I do mean impossibly large:  the number of credits shown as won is way larger than the actual top jackpot on the machine.  (It might say you won $166 million when the most it's even possible to win is only $99,000, according to the paytable that the machine shows.)  In most cases of a display error, the players didn't even line up the symbols in a winning combination for the top prize.  Cases like this are simply programming errors.

Some players might wonder, "If these slot malfunctions happen, how can I trust the game at all?  How do I know that it's not ripping me off all the time.?"  It's a fair question.  The answer is that the random number generator (RNG), the heart of the machine, is completely separate from the part that controls how many credits are displayed.  The RNG is subjected to rigorous testing by the game manufacturer, and, in many cases, by the governmental agency that regulates gameplay in whatever jurisdiction the game operates.  Further, both the casino and the agency can run diagnostics on demand to test the RNG and other aspects of the game.  In short, the occasional display error doesn't suggest that the overall game itself is faulty.

Below are some examples of machines telling players they won more than they actually did.

An Oklahoma woman's machine said she'd won a staggering $8.5 million, proven by the photo she snapped of it.  The casino said it was a malfunction and refused to pay.  The picture the player took is of admin screen and not a game screen (which none of the reporters noticed), but it does show that the player lined up the jackpot symbols on the top line, so it seems she did legitimately win the top jackpot.  The question then becomes, what was the top jackpot supposed to be?  Not $8.5 million, because only statewide progressives like Megabucks go that high.  All of the reporting on this case was really sloppy, with no reporter bothering to mention what the top jackpot on that machine really is.  Since everyone else dropped the ball, I called the casino myself and they verified that they've seen the top progressive jackpot go only as high as "almost $200,000", but that's for the whopping $25 denomination.  The screen shows the player played $1.25, which would be 25¢ x five lines, for which the jackpot is much lower.  The player seems to have legitimately win the top jackpot, whatever it was (displayed on a marquee on top of the machine), but not $8.5 million, which it was not.  It's hard to know whether this was a display error or a setting error, but it was definitely one or the other.  Feb. 2020, Newcastle Casino; Newcastle, Oklahoma (Fox 25)

Katrina Bookman's machine told her she'd won a whopping $42.9 million.  That would have been the largest slot machine jackpot in U.S. history were it actually legitimate.  As a computer programmer, I can tell you exactly where the winning jackpot figure came from: Computers work off multiples of 2, and 2 to the 32nd power is 4,294,967,296. Put in decimal for the cents, and you get $42,949,672.96, almost exactly the amount shown in Ms. Bookman's selfie.  (Yes, her selfie shows 20¢ less than that; she probably gambled away 20¢ before realizing that the machine was telling her she had $42.9 million in credits waiting.  The $42,949,672.96 power of two is so close to the $42,949672.76 displayed on the machine that clearly this is the source of the malfunction.)  The question then becomes, of course, what caused the machine to display that amount?  The answer is that there's simply some kind of error in the programming code.

While it's clear that Bookman didn't really win, the casino's reported offer to Ms. Bookman was stingy: a free steak dinner.  Really?  After delivering the soul-crushing news that she hadn't really won multiple millions of dollars, the casino could have, and should have, offered her much more.  She's suing, and doesn't have any realistic chance of winning, but the negative attention might convince the casino to simply give the player the reasonable compensation they should have offered in the first place. Aug. 2016, Resorts World, Jamaica, Queens, NY  (CNN)

Veronica Castillo had a decent spin on the Jurassic Riches machine (see picture at right), which should have paid 210 credits.  Instead, the machine said she'd won 171,787,374 credits, which on her 5¢ machine would be $8.6 million dollars!  The top jackpot available on the machine is only $20,000, and based on the number of lines and credits Castillo was playing, the most she could have won was $6000. 

Tellingly, this is exactly the same kind of error as Ms. Bookman experienced above.  The 171,787,374 credits shown, multiplied by an even 25, is 4,294,684,350, which is too close to the 2^32 listed above to be coincidence.  The slot is apparently keeping track of the credits at a 0.2¢ denomination, and then converting to whatever denomination is actually being played.  Lucky Eagle Casino in Rochester, WA, 11/2/15 (Daily Mail, Lucky Eagle's statement)

Behar Merlaku lined up only four of the five jackpot symbols on his machine, but the slot told him he'd won $58 million.  More specifically, it told him he'd won 43 million euros.  If that number looks familiar, it should: it's the same as in the cases above, and the result of the same kind of programming error.  This amount isn't just more than the biggest jackpot ever won, and isn't just more than the actual top payout of the machine, in this case it's actually more than typically allowed by Austrian law, which is two million euros.  Despite this, as with almost every other case, the player insisted on getting paid the full amount and filed a lawsuit. Bregenz casino, Austria • March 26, 2011 (Yahoo News, Daily Mail)

Louise Chavez had the fortune of her slot telling her she'd won in impossibly massive jackpot.  She then had the devastation to hear from a casino employee that the machine had simply malfunctioned and she hadn't really won at all.  The amount that machine said she won was...wait for it...$42.9 million.  Exactly the same as for the other cases above.  Of note, this is one of the rare cases in which the player didn't sue the casino. Fortune Valley Casino, Central City, CO (ABC News)

Bill Seebeck was playing Bally Ultimate Party Spin when it told him he'd won $167M.  Which is absurd, since that's four times the largest slot jackpot in U.S. history.  The max payout on Seebeck's machine is only $99,000, and only $2500 for the $1.50 per spin that he was playing.  Hard Rock Casino, Tampa, FL • Nov. 1, 2009 (Sun Sentinel)

The slot that Ly Sam was playing told him he'd won $55 million.  As per usual, this is not only more than the actual top jackpot on the machine ($46,000 or $95,000, depending on which article you believe), it's more than any jackpot ever won on any slot machine, ever.  It doesn't seem that the player actually lined up the jackpot symbols, because the few articles I found made no mention of the symbols.  As usual, the player sued, and in a surprising move, the court ordered that the player be paid.  The casino of course appealed, but I can't find any further information about this case, probably because it's not being covered much if at all in the English-language press.  Sheraton Hotel, Sept. 25, 2009   (Talk Vietnam, South China Vietnam Post)

Twice, a video poker machine told a certain player that he'd won a million dollars.  Unfortunately for him, the top prize on the machine was $40,000.  As a result of the glitch, the Ontario Lottery and Gaming Corp. shut down all 296 of its video poker games while the gaming commission investigated.  The player was paid $1000 and $4000 for his wins.  Rideau Carleton Raceway, Ottawa, Canada • June 2009  (The Star)

Paul Kusznirewicz's "Buccaneer" machine said he'd won an incredible $42.9 million prize.  You'll remember that number from several of the cases above, meaning it's the result of the same kind of programming error.  Anyway, the top prize in Mr. K's machine was only $9,025.  News reports don't give a lot more details about this particular case. Georgian Downs Casino in Innisfil, Ontario, Canada, Dec. 8, 2008  (The Star)

Gary Hoffman thought he won $1.6M on the slot machine he was playing, because that's what the slot told him.  As usual in cases like this, he ignored the fact that he didn't even line up a winning combination, as well as the fact that the top payout on the machine he was playing was only $2500.  And as usual, he sued in district court.  And as usual, he lost.  (The court dismissed the suit.)  He appealed to the NM Court of Appeals, which upheld the decision of the lower court.  He then appealed to the U.S. Supreme Court, which declined to hear the case.  Usually the player loses in court because the casino has evidence of a malfunction, but in this case, the casino was owned by a Native American tribe, which can't be sued because it has sovereign immunity.  As one attorney said, "You can't sue the state of New Mexico in Texas."  Sandia Casino, NM • Mystical Mermaid by IGT • Aug. 16, 2006  (Albuquerque Journal, ABC News)

Setting errors

When a slot is set up incorrectly it can result in another kind of error.  In these cases the machine doesn't malfunction: it functions according to the way it was programmed, but that programming is screwed up.  Here are a couple of cases of this.

In the first, Imperial Palace casino in Biloxi, MS ordered a flat-top slot from IGT, but IGT accidentally set it to be a progressive.  The signage on the machine said the top payout was $8000, but when the player lined up the jackpot symbols, the screen said she'd won 200,000 credits, which at $5 per credit would be a cool $1 million.  Of course the casino refused to pay, the player sued, and lost.  The court ruled that the $8000 payout listed on the display constituted the contract between the casino and the player. (FindLaw)  This case was discussed in some detail by players at the Wizard of Vegas forums.

In another case, 87-year-old Pauline McKee was playing a Miss Kitty slot at the Isle Casino in Waterloo in 2011 when it told her she'd won a "Bonus award" of $41,797,550.16.  The top payout on the machine was supposed to be only $10,000, and that's what was listed on the machine.  The slot maker (Aristocrat) knew that the false bonus could be triggered, and had recommended that casinos stop using those games until they could be fixed.  Isle Casino didn't.  The casino's compensation to the player was ridiculous: $11.85.  Seriously.  Of course the player sued, and the Iowa Supreme Court sided with the casino. (WaPo)

Mechanical Errors

With video slots, the common malfunction is that the machine shows a bunch of credits won, even when the player didn't line up the jackpot symbols.  With electro-mechanical (physical-reel) slots it's the opposite: the jackpot symbols line up, but the machine says the player won nothing, or just a small amount.  In these cases, the computer inside the machine has chosen the correct combination to be displayed, but for whatever reason, the physical reels don't actually display what the computer chose.

The typical reasons this happens is because the coin or bill acceptor is jammed, or the machine thinks someone's trying to open the cash door.  When that happens, the reels will either stop immediately (rather than stopping on the combination the computer chose), or spin backwards until the error is cleared, where again, they'll stop suddenly, and not on the combo chosen by the computer.  When the reels stop suddenly, it's possible that the jackpot symbols might happen to all land on the payline.  But if so, that's just a side effect of the sudden shutdown; the reels didn't stop where they were supposed to stop.

Las Vegas butcher Joe Pepitone thought he won $463,895 on a slot by lining up the jackpot symbols.  In fact, the coin acceptor was jammed, so the slot went into error mode, spinning the reels backwards until the machine could be reset, at which point the jackpot symbols happened to line up.  But that wasn't the combination chosen by the computer when Pepitone pressed the spin button.  He filed a claim with the gaming commission, which ruled against him.  He then filed a case in district court, which also gave him no relief.  He appealed to the Nevada Supreme Court, which yet again sided with the casino.  Arizona Charlies, Las Vegas • Nevada Nickels slot by IGT • Oct. 1997  (Las Vegas Sun, 2000, 2001)

Cengiz Sengel had a similar experience.  The bill acceptor signaled that the cash door was open, so the machine shut down immediately, causing the three jackpot symbols to be displayed on the payline.  After the casino refused to pay the $1.8 million jackpot, Sengel took the Nevada Supreme Court, which ruled against him. Reno, 1996  (Las Vegas Sun)

Online game errors

Lisa Piluso was playing the online game Capital Gains at Caesars Interactive, thought she'd won a jackpot because a software bug meant that bonus symbols didn't get erased from the screen when a new round started.  This is straightforward:  She didn't win, but of course she's insisting that she did, and of course has filed a lawsuit. (Philly Voice, 2021)

In another case, Jacqueline Davis of Detroit thought she won $3 million playing roulette online at BetMGM.  Reporting is sketchy, but what we know is that the game credited her for winnings that she didn't legitimately win.  Predictably, the player sued.  I spoke with the attorney handling the case for the player (here's the summary), and I reviewed the legal complaint which I predicted would fail for various reasons (here and here), including that BetMGM's alleged failure to timely report the malfunction to regulators doesn't mean that BetMGM has a legal obligation to pay malfunctioned winnings.  Two years later, that was exactly the conclusion that the court came to.  I should have been a lawyer. Game play in 2021 • (Initial reporting from Newsweek 2021 • MI Lawyers Weekly, 10/23) 

No winning combo AND no payout display error

In the cases above, the player either lined up the jackpot symbols, or the machine told them they'd won.  But there's a third situation in which neither happens, but the player still thinks s/he won anyway.  Here are some cases like that.

April 8, 1995 • $1.7M jackpot • Cool Millions slot.  The player said she played three credits (necessary to win the top jackpot), and lined up all three jackpot symbols on the payline.  The casino said she played only one credit, and that one of the jackpot symbols was above the payline.  The player was possibly lulled into believing she'd won because the machine had gone into a hopper tilt (the coin acceptor was jammed), which caused the slot to flash its top light and make a loud noise.  That's to notify casino staff that the machine needs to be serviced, not that a jackpot has been won.

The computer logs from the machine corroborated the casino's version of events, and the Mississippi Gaming Commission ruled that the player hadn't really won the jackpot.  The player appealed to a circuit court, which sided with her and ordered that she be paid.  They based this not on evidence that she actually won, but that the casino had failed to protect the evidence:  For example, their security cameras failed to record the dispute because the tapes were being changed at the time, they opened the machine and messed with it before the Gaming Commission agent arrived, and they put the game back in play before the agent arrived.  The gaming commission and the slot maker (which would have had to pay the progressive jackpot) appealed to the Mississippi Supreme Court, which reversed the lower court's decision, and ruled that the player hadn't legitimately won the jackpot, but criticized the casino's handling of the situation.  Effie Freeman, Splash Casino in Tunica, MS (FindLaw, Las Vegas Sun)

Oct. 14, 1995 • $2.7M jackpot • Cool Millions slot.  Extremely similar to the 4/8/95 case below, right down to the brand of slot machine:  A player said he lined up the jackpot symbols, the casino said he didn't.  The Mississippi Gaming Commission sided with the casino.  The player appealed to a court of law, and after losing there, appealed to the MS Supreme Court, which also sided with the casino, but which again reprimanded the casino for spoiling the evidence which hurt the player's claim.  James Thomas, Isle of Capri Casino in Lula, MS. Slot made by Casino Data Systems  (MS Supreme Court)

Nov. 16, 1997 • $509k jackpot • Grand Bucks slot.  Very similar to the 4/8/95 and 10/14/95 cases above.  A player thought he won the progressive jackpot, the casino said he didn't, and the state gaming commission sided with them  The player appealed to a Mississippi court, which sided with the player because the casino had foolishly destroyed the evidence.  The casino appealed to the MS Supreme Court, which sided with the player and ordered that he be paid, probably because the court was getting tired of all these cases in which casinos failed to properly preserve evidence.  Note, the court didn't argue that the player had legitimately won the jackpot (they noted that he likely had lined up only two jackpot symbols).  Instead, the casino simply screwed itself by failing to safeguard the evidence properly.  David Hallmark, Grand Casino Biloxi, MS  (FindLaw, I. Nelson Rose)

Other cases

Slot machine  failed to inform player that he won

Here's a new one:  A slot at Treasure Island malfunctioned and didn't tell the player that he'd won $230,000.  Lucky for him, the Nevada Gaming Control Board tracked him down so his prize could be awarded. (CNN

Blackjack side bet in online game

In 2018, online casino Betfred denied U.K. gambler Andrew Green the £1.7M jackpot that the software said he won as a side bet in a blackjack game, but which the casino said was the result of a malfunction.  Green sued for the full amount and won his case in 2021.  I can't comment on the type of error because all of the reporting on the case is pretty bad, none of it explaining anything at all about the nature of the alleged malfunction.  (If you can find better reporting that explains the supposed problem, please let me know.)  (The Sun)

Players who exploited bugs

John Kane and Andre Nestor found a bug in Game King that let them easily win jackpot after jackpot just by pressing the buttons in a certain order.  They racked up hundreds of thousands of dollars in wins, but were then arrested and charged with hacking.  It was a stupid accusation, but being innocent doesn't protect you from being arrested.  The charges were eventually dismissed, but the duo suffered ten days in jail, a long and harrowing legal journey, and untold legal fees. (Wired, 2014)

Play slots online

I suggest you play something other than slots because slot odds are so bad.  You could also play online with fake money, because then it doesn't matter if you lose.  A good casino for free-play is Bovada, since it requires no download and no registration.  (If you see a registration box, you can close it and continue without registering.)  You can play with real money too, though I hope you won't (or at least won't bet more than you can comfortably afford to lose). (advertisement)

All my slot machine articles

  • Slot machine basics.  How much it costs to play, how much you can win, expected loss, why they're a bad bet, why they're popular, how you can limit your losses, speed of play
  • How to play slot machines
  • Slot returns.  How much they pay back.
  • The Randomness Principle.  Slots don't continually get looser and tighter as they're played.  They don't have to.
  • How they work. Explains the randomness principle, and runs through the math to show how a game returns a particular payback percentage.  There's a companion page on Par sheets.
  • Slot Machine Myths
  • Slot Machine B.S.  Wrong info that's published elsewhere.
  • Strategies. Tips for increasing your chances of winning, and saving money.
  • Slot Jackpots.  Odds of hitting the jackpot, progressive jackpots, and other jackpot topics.
  • Biggest Jackpots.  The largest slot and table game jackpot wins in Vegas.
  • Skill-Based Slots.  The scoop on the new games in which your results aren't entirely determined by chance.
  • Slot Machine malfunctions. How and why slot machines screw up, causing players to think they've won the jackpot when they really haven't.
  • Slot Machine Simulator.  I programmed an exact replica of the Blazing 7s slot (odds-wise).  Click it to play thousands of spins in one second and see how you do.
  • Slot name Generator.  Randomly creates a slot machine name using common slot words.  Hilarious!

Practice gambling with play money

Before you throw down your hard-earned cash in a casino, PRACTICE FIRST!  Learn the games with play money where it doesn't cost you anything if you lose.  Seriously.

You can play Bovada's games (below) right away without registering for an account.  Most every other online casino makes you give up your email address just to play the fake-money games — ugh.  That's the main reason Bovada is the only online casino that gets advertising space on my site.  (When you see the registration box, you can cancel it and proceed to the game without registering.)

Play blackjack


Play roulette


Play craps


Play baccarat


Approved by Casinomeister

Proud not only to be an approved Webmeister by Casinomeister,
but also to be one of the very first approved. (#7, May 2020)

Site Contents ©2001-2024 Michael Bluejay Incorporated.
I believe everything herein to be accurate, but I'm not responsible for errors or omissions.  I'm pretty irresponsible, actually.

Home |  About Us   Contact  |  Updates  |  Privacy          Gambling Problem? Call the 800-522-4700 hotline, see horror stories, and know that aripiprazole and Parkinson's drugs encourage gambling.

Play:  Slots  •  Blackjack  •  Craps  •  Roulette