The Most Embarrassing Software Bugs in History

Writing perfect code is impossible. People often say that there is no software that is completely bug-free. Here are our top most interesting, embarrassing, or devastating bugs until now.

AT&T’s Long-Distance Network Collapse (1990)

At that time, AT&T’s long-distance network carried over 70% of USA’s long-distance traffic and routed more than 115 million phone calls. The backbone of the network was a system of 114 switches (4ESS) that were scattered across the country. Each of these switches was capable of handling up to 700,000 calls per hour.

The problem was an update on the software that controlled these switches. A switch in New York performed a self-test which indicated that it was near its limits. Thus, the switch reset itself, which usually took about 4 seconds. This happened to all 114 switches in the network which blocked 50 million calls in 9 hours until the engineers found a way to stabilize the system. This cost the company $60 million.

The Pentium chip’s math error (1993)

Due to a programming error, Intel’s Pentium chip was quite bad at math. Because of this bug, the processor returned incorrect binary floating-point results when it was used to divide numbers. According to the manufacturer, the bug would occur every 27,000 years, while according to IBM it would happen every 24 days. However, the bug went on to be unnoticed for a whole year, so the man who found it stated that it was probably less harmful than IBM stated.

The Mars Climate Orbiter disintegrated in space (1998)

The Mars Climate Orbiter was a 338-kilogram robotic space probe that was launched by NASA on the 11th of December 1998 to study the atmosphere, climate and surface changes on Mars. But on the 23rd of December 1999, the $655-million spacecraft went into Mars’s upper atmosphere in the wrong angle, which made it burn up in the process. The problem was that the thrusters’ output was counted in pound-seconds rather than Newtonian seconds.

Windows locked out non-software pirates (2007)

A Microsoft server problem in 2007 caused the company’s WGA validation system (Windows Genuine Advantage) to falsely accuse users of the Windows XP and Vista of running pirated software, which resulted in the disbanding of a bunch of features for the said users until the issue was resolved.

The problem lasted for 19 hours and caused users to post messages about it on Microsoft’s forums. One of the features that were disabled for legitimate users was Vista’s Aero graphical interfaces, and the frustration of the users reached significant levels before the issue was fixed.

Apple Maps gave us directions to nowhere (2012)

Before 2012, Apple used Google Maps on its iOS devices, since Google is their rival, they decided to develop their own app that would replace it. However, in Apple’s Maps, whole tourist attractions, lakes, bridges and train stations were mislabeled or entirely missing. This data comes from dozens of various databases including satellite photos, roads and points of interest. Meshing all of them together takes much more than smart software, it also needs thousands of hours of handwork. Google had years to complete it, but Apple didn’t.


Coy, P. & Lewyn, M. (1990, January 29). The day that every phone seemed off the hook. Business Week, pp.39-40.

Fisher, K. (2007, February 26) Windows Genuine Advantage’s newest setting: You might be a pirate. Ars Technica.

Garside, J. (2012, September 20). Apple Maps service loses train stations, shrinks tower and creates new airport. The Guardian.

Halfhill, T. (1995, March). An error in a lookup table created the infamous bug in Intel’s latest processor.

Oberg, J. (1999, December 1). Why the Mars Probe went off course. IEEE Spectrum.

The most embarrassing software bugs in history

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