Mistakes — we’ve all made a few but some are much harder to fix than others. A handful of the most disastrous errors could cost you your job.

These days, many of the most terrible workplace gaffes seem to relate to technology, and they occur most frequently when people are starting out in a junior role.

BBC Capital decided to dig a little deeper. Here we shed light on some of the worst mishaps revealed by interns as they learnt the ropes.

We went to online question-and-answer site Quora to uncover some of the answers to What is the most catastrophic mistake made by an intern at a tech company?

Gil Silberman, a lawyer and social software entrepreneur, got things off to a roaring start as an intern. He wrote that in “my first high school coding job — I guess that made me a tech intern — I burned down the entire office due to a cabling mistake. It was a total loss, displaced 100-plus people, and destroyed lots of files, records, artwork, and a lot of the CEO's memorabilia. He never blamed me, but I think he knew it was my fault.”

Yet, Silberman wrote that he has made some amends — however indirect: “After a couple decades in Silicon Valley, I think I've finally created more wealth than I've destroyed so I guess the world and I are even now.”

Jay Bazzinotti described a career-ending mistake by an intern, which also brought the FBI to his firm. Years ago, Bazzinotti worked at a company that helped invent the error-correcting modem, a technology which helped transmit data reliably. The company often hired interns, and treated them as equals, something that didn't happen often in the industry at that time. “We didn't send them out for coffee — we immersed them in the work and rewarded them when they contributed. We had one intern we particularly liked. He was quick and bright, and he provided real contributions to the technology.”

Then, disaster struck. Bazzinotti relates that one day, the FBI arrived at his offices. He wrote: “They came in fast and hard and all work came to a stop while we wondered what the hell was going on. It turned out that our intern had stolen the source code for our most precious and valuable techniques and tried to sell them to the Chinese for the pitiable sum of $50,000.”

He wrote: “His [the intern’s] life was ruined and as I said, the amount of money he was seeking was ridiculously small considering the technology made us 100s of millions of dollars. I would say this rates right up there with the biggest intern gaffes in history.”

Winnie Wu, a Facebook intern, wrote: “I joined at the beginning of my internship under the username www (they are my initials), and all the engineers' sandboxes started to redirect to mine because of the url address. So yes, I managed to break things without even writing a single line of code.”

Far-reaching impacts

While at university in 2002, web operations expert Oleksiy Kovyrin worked on a project to build a huge wi-fi network in Ukraine. When doing some “de-bugging” he received an alert saying the core router had some problems.  

“And that's where things went wrong... When I wanted to shut down my local server … (I) typed "poweroff", pressed enter and only then realised that I did it on a wrong server. I had that second window opened ever since the monitoring alert an hour ago and now I've shut down the core router of our city-wide network.

“We had to grab a car and drive to the central station to power the router back on, our whole banking infrastructure was down for 30-plus minutes and that was one of the darkest days of my career.”