Even the best laid plans can have a chance of failure. Maybe something was overlooked. Someone with obscene amounts of resources would start a new plan from stage one, but often that's not possible. The previous action had some success, and to implement a completely new path could require a lot of resources and time, which may not be available. An entirely new option would be like using a new fuel source for your house every time a light bulb goes out.
A rational response would be to just fix what was already there, making sure that the problem that arose is less likely to happen again. Unfortunately, it still will, specifically because of the fix.
When someone tries to solve a problem, the solutions counteract each other, making a negative outcome easier (or possible). Depending on the consequences, this could be Played for Laughs, Played for Drama, or both. Simplified, it could be like flipping a switch, then flipping it again, not realizing it had been done the first time.
Consider Didn't Think This Through, when one person does it. Because this requires some knowledge of what went wrong previously, the fixes may have been thought through, just not for every possible interaction, or maybe even overlooking exceedingly obvious interactions.
Compare Tragic Mistake, Hoist by His Own Petard, Didn't See That Coming, Right Hand vs. Left Hand, Gambit Pileup, "Gift of the Magi" Plot, Abilene Paradox, and Too Many Cooks Spoil the Soup. Alternatively, "Nice job breaking it, hero/fixing it, villain!". Dick Dastardly Stops to Cheat is a Villain Ball Sub-Trope. If pulling this on another party is part of a gambit, it can overlap with Kansas City Shuffle.
Since at least a temporary Bad Ending is the point of this trope, expect some spoilers.
- In Death Note, both Light and Mikami decide to kill Takada after she gets kidnapped and has outlived her usefulness. Unfortunately for Light, and fortunately for Near, Mikami's decision to kill her on his own without checking with Light first ends up leading Near right to his Death Note, thus spannering Light's plan to prevent Near from finding it.
- In the Cowboy Bebop episode "Cowboy Funk," Andy and Spike find themselves trapped in an elevator and speeding toward an armed explosive. Spike confidently reveals that he had planned for such an event and had reset the security code on the elevator's manual override. Andy confidently reveals that he had done the same thing... thus RE-resetting the code to its original setting and locking them both out.
- In Ultrasonic, during a battle with an akuma called the Chemist. Ladybug manages to separate her from her weapon, a possessed beaker, and she throws her yo-yo at it intending to break it. At the same time, Chat Noir chases after the beaker and would have been able to grab it in time if the yo-yo hadn't hit his hand and caused him to knock it away. As such, the Chemist gets the beaker back and the fight gets drawn out.
- In Diamonds Are Forever, James Bond and the Bond girl both have the idea of swapping the control tape for Blofeld's Kill Sat with a fake. Result: the real tape gets swapped right back into the machine. In fact, she thought he was slipping her a fake tape as a signal that she should make the switch for him since he'd been captured. He was actually just trying to get her to get rid of the control tape he had already switched out, so the guards wouldn't find it on him if he was searched.
- In the political satire The Rise and Rise of Michael Rimmer, just as the eponymous Rimmer is about to stage a popular coup one of the people he's pissed off attempts to shoot him from a high window while another is preparing to throw a bomb. Unfortunately the gunman falls out of the window onto the bomber, and the bomb goes off next to them.
- In the sex comedy The Naked Detective, three simultaneous attempts on the life of Harthcourt Higglesbotham III just wind up canceling each other out. His fourth wife Roxanne tries to kill him with rat poison (which kills via blood thinning)—while his nurse Annie tries to overdose him with vitamin K medicine (which is a coagulant). The drug interactions still send him into seizures, but his daughter-in-law Irene tries to shoot him and completely misses—and the resulting adrenaline spike allows Higglesbotham to survive the seizures. And then he gets accidentally killed by antacids contaminated with bug spray.
- In one of the Star Trek novels written by William Shatner, two independent groups are trying to rescue hostages from a base in low orbit around a planet. Saving them requires destroying either the main power generator or the backup power generator — but not both, as that would cause the base to lose orbit and everyone to die. One of the groups chooses to disable the main generator for their rescue attempt, while the other group chooses to disable to backup generator. Both put their plans into motion at exactly the same time. Tragedy results.
- In the Doctor Who Missing Adventures novel Cold Fusion the Doctor does this to himself. There are some galaxy shattering grenades that can be disarmed by reversing the polarity of the neutron flow, which he does so he can fake out the villain by pretending that they've won when they send the duds to the target. Then his past self finds the grenades and re-reverses the polarity thinking he's the one disarming them. Which means the bombs are live when sent to their target.
- One of G. K. Chesterton's Paradoxes of Mr Pond, "The Three Horsemen of the Apocalypse," concerns a field marshal whose soldiers were too eager to obey his orders. The marshal sent the first of the three horsemen with orders to execute a politically troublesome poet; when the prince arrived, fully aware of the marshal's intentions, he sent a second horseman to carry a reprieve. The marshal then sent a third horseman with orders to shoot the second; unfortunately, the first horseman surmised the second horseman's purpose and shot him, so the third horseman ended up shooting the first horseman by mistake. As a result, the execution order never reached its destination, and the poet went free, much to the marshal's consternation.
- The Russian fable about Yeruslan Lazarevich includes him battling a king who can only be killed by a particular sword. The sword lies under the head of a giant who already tried to fight him. Fortunately for Yeruslan, the head is still alive, and warns him of the catch — strike the king only once. A second strike will heal him.
- Jeeves and Wooster has countless moments of this. Probably the most excruciating example is Gussie Fink-Nottle's famous school awards speech, brought about because both Bertie and Jeeves had spiked his orange juice with alcohol in the hopes of curing him of his nervousness. They succeeded. Oh, and Gussie also decided to have a drink to steady his nerves.
- Who Put the Pepper in the Pot? A family is having stew for dinner, and you can guess what happens.
- In Air Crash Investigation, many of the incidents are caused by a maintenance job that was done correctly save for one minor detail, or by a perfectly copacetic repair job that somehow introduced a problem or allowed an unknown pre-existing problem to start wreaking havoc.
- In one Mad About You. Paul & Jamie left their apartment in the middle of the night still in their pajamas. Paul "pushed the little button" which deactivates the latch lock on the door so that they could get back in and not have to take their keys. Jamie doesn't know that Paul did that so she pushes the little button too, so now they're locked out but don't discover that until they come back from whatever adventure they had.
- Gilligan's Island:
- On one an episode, a homing pigeon landed on the island, and the gang realized they could send a note home with it. The Professor said the pigeon was too thin to make the trip home, however, and needed to fatten up with a proper diet and exercise. But the rest of the gang, impatient to leave, overfed the bird, and the next morning the bird was too fat to make the trip.
- On another episode, the Skipper had both insomnia and was sleepwalking when he did sleep. The Professor got the idea of borrowing Mr. Howell's tranquilizers, and putting them in the Skipper's coffee; but then, not knowing he had done so, Ginger put another one in his coffee; and not knowing either of them had done so, Mrs. Howell added a third, and so on, until the Skipper noticed the pills and added one himself, drinking six of them. (Gilligan, amazingly, was completely innocent here.) It helped him sleep, but suffice to say it took a long time for him to wake up.
- During a war games exercise in an episode of Gomer Pyle, U.S.M.C., Sergeant Carter gives the unwitting Pyle a false plan with the expectation that he'll get caught and reveal it to the opposing team through his own incompetence. Unfortunately, when Pyle does get caught, he decides to fool the opponents by giving them a fake target... which is the exact one Carter had been planning to attack in the first place.
- In an episode of ChuckleVision both Chuckle brothers try to turn off the Earth-destroying weapon of Ping the Pitiless. As a result it gets turned back on.
- In the multi-Doctor Doctor Who episode "The Day of the Doctor", the Tenth and Eleventh Doctors both point their sonic screwdrivers at the time portal to Reverse the Polarity.
Eleventh: It's not working.
Tenth: We're both reversing the polarity.
Eleventh: Yes, I know!
Tenth: There's two of us. I'm reversing it, you're reversing it back. We're confusing the polarity!
- In one episode of M*A*S*H, the entertainment division keeps sending boring movies to the 4077th. Pierce and Hunnicut get wind of a film that was released without approval of The Hays Code, and pull strings to get a few labels switched. Colonel Potter, meanwhile, pulls strings to get the good movie sent to the 4077th...
- Not an infrequent problem on Worst Cooks in America. For example, one instance in season 2 (after two of the contestants had their teams swapped) involved a newcomer to Anne Burrell's team making mashed potatoes. He had remembered that the proper way to prepare the potatoes involves salting the water in which they were boiled. However, two of his new teammates were afraid that he didn't know that unsalted water for boiling potatoes is one of Chef Burrell's big no-nos, so they both made sure to add "enough" salt. Sure enough, when the chef checked on the water, she found it way too salty to use. Luckily, she checked this and warned him before he put the potatoes in the water.
- One episode of 30 Rock has Tracy and Jenna try to solve people's problems, declaring themselves "The Problem Solvers," wearing shirts that say "The Problem" and "Solvers." Unfortunately for them, they're standing side by side in such a way that their shirts read "Solvers The Problem." Jenna asks whether they should switch shirts or positions, to which Tracy says "Just to be safe, let's do both," resulting in their shirts still reading "Solvers The Problem," but now Jenna's shirt is too big, and Tracy's, too small.
- Portal 2: During the final levels most locations need repulsion gel, propulsion gel or conversion gel, which is usually pouring out of a broken pipe. So during the boss fight, all pipes are sealed, leaving you without gel or even portals. As you can no longer use portals, Wheatley happily throws bombs at you, knowing you can't send them back like you did in the first game. Thing is, the bombs are more than capable of breaking those pipes, spreading conversion gel which lets you place the portals needed to throw back the bombs. This is understandable, given who Wheatley is. The bombs were also wholly redundant based on the immediate flow of neurotoxin. More patience would have meant a win anyway.
- The Powerpuff Girls episode "Monkey See, Doggy Two" is about Mojo Jojo trying to revise his plan from a previous episode. There he turned the Powerpuff Girls into dogs with a magic statue, but one of them chomped him in the ass, he dropped the statue, and it breaking turned him into a dog. To correct this, Mojo took two "precautions": First, he covered his butt with a steel plate, which would've been all that was needed. Second, he refused to turn the girls into dogs, which was a pretty bad decision, but turning them into dogs didn't work the first time. However, that problem would've been remedied by the butt plating. Telling the girls how he fixed his mistakes = pretty stupid. All three combined just lead to a normal beatdown.
- In The Simpsons, Apu and his wife Manjula had trouble conceiving a baby. Then they started to use fertility drugs—unaware that Homer, Marge, and Bart were independently slipping some into Manjula's food. The combined dosage was so high they end up with octuplets, and almost going broke due to the resulting expenses.
- A SpongeBob SquarePants episode featured a giant worm terrorizing Bikini Bottom, and Sandy deciding to go after it. Not believing she had a chance of winning, the citizens pushed the entire town into another area. Guess where Sandy drove the worm.