Programmers, what is the biggest fuck up you’ve ever seen caused by a tiny mistake in the code?

There was a leave application at a company I was working for, it was a nice 30k employee strength software company.

The leave application had a workflow built in. If an employee’s leave wasn’t approved by his manager for 3 days it would go to the next level manager and stay there for 5 days and so on..

To test some aspect of this workflow feature, the approval waiting time was reduced from x days to 3 mins. Then without reverting this test change the code was pushed to production.

The next day, the company’s CEO had around 500 leave applications in his mailbox.

A co-worker made a change to our credit card processing code on a Friday evening, didn’t test it, pushed it to prod, and then went home.

He made a typo in his code that caused a runtime error on the backend. Everyone that tried to make a purchase received a generic “Couldn’t process your card. Please try again.” But it did process their card… it was failing at some step after. People would retry several times and their credit cards were being charged every time.

Super cluster fuck on Monday morning.

During work experience me and my friend went to the schools IT department and had been tasked with building and programming robots as well as making a presentation on how to recreate our results. They were remote controlled except they all shared the same radio channel so due to a single line of code 1 controller controlled 8 robots

Although the issues with THERAC-25 were caused by more than a tiny mistake, the magnitude of the fuckup means it deserves to be here.

When I got my degree, this accident was required reading as part of the intro course.

Our payroll system used to take about twenty minutes to run so the run was saved in a file named for the date and time to the minute. That file is then uploaded to do direct deposits or print checks. With faster computers now, we’ve had several customers run more than one run in the same minute so the first one gets overwritten. Fortunately those runs were usually small since you couldn’t get through them quickly enough to finish in the same minute, but we found that had happened several times over the past few years. We had to have customers fix payroll problems in previous years which was just a mess for their accounting including amending tax returns. All of that because the programmer wanted to save two characters in the filename.