One thing that may happen to you at any time when playing a slot machine is that the machine could have malfunction. If that happens, when say you are visiting a bricks and mortar casino then the slot attendant or slot mechanic will simply reset the machine and it will then return to the exact state of play as it was when it did malfunction.
As such if you were part way through playing off a bonus game you will not lose any winnings, as when reset that bonus game will then continue to play off.
There have however been several incidents over the years were a player won a jackpot but the machine displayed on its screen a jackpot way higher in value than the one won. In such circumstances commonsense should prevail and that player should be paid out the jackpot they did win and not the erroneous figure displayed on the slot games screen.
However, when you experience an online or mobile slot machine malfunction you could be in for a very long and drawn out battle with the casino.
For the first thing the casinos support staff will tell you to do is to close and then reload their software, or if playing via an instant play gaming platform they will tell you to shut down the window of the web browser and clear the cache and possibly clear the cookies and history of your web browser and then reload the game.
If that doesn’t work and the slot will not reload or does not return you to the bonus game you were playing off, if that is when the slot malfunctioned they will then refer it to the company who supplied them with that game and/or their gaming platform.
You can often find it takes weeks for that malfunction to be investigated and often once it has been you will get nothing more than the stake returned to you for that one single spin.
If you had just triggered a bonus game and the slot game did malfunction then being paid back just your stake is going to leave you feeling very disappointed if not very angry, for you could have won a large amount of cash from that bonus game.
Fortunately such situations are fairly rare online and on mobile gaming platforms and apps, however they can arise from time to time and it is always going to be the case you will be left completely at the mercy of the casino operator or the company supplying the gaming platform and games to that casino site in regards to whether they will award you with any additional compensation for that malfunction, other than just a refund of your stake money.
Many players now film themselves playing slot machines, and maybe that should be something you do yourself, as by doing so if a slot machine does malfunction you have visual proof of it doing so, which may give you a little more leeway in regards to getting a much fairer payout if a slot machine did crash or malfunction when there was a chance you could have won at that moment in time, such as when you were part way through playing off a bonus game!