leap-year

List of 2024 Leap Day Bugs

Matt Johnson-Pint

• 8 min read

Well, it's 2024 and leap day has come once again. As I've done in prior leap years, I've captured as many bug reports and outages as I can, along with links to the source where possible. For those have been following along, you'll notice these have been organized a bit better now! I've sorted them by degree of impact - as I perceive it to be.

You may also be interesting to seeing the shenanigans from 2020 and 2016.

Last updated 2024-03-01 6:18 PM PST

Highest Impact

  • Many petrol stations in New Zealand experienced problems with self-serve payment terminals, including Allied Petroleum, Gull, Z Energy, Waitomo, and BP - reported by Wired, The New Zealand Herald, and many others. The issue was reportedly related to Invenco payment solutions terminals. Invenco Group's CEO John Scott confirmed that indeed there had been a leap year glitch in their software. The bug has since been fixed, and an update was rolled out to their network of payment terminals worldwide.
  • Payment terminals at ICA grocery and pharmacy stores across Sweden failed to process transactions on February 29th, according to various reports (1, 2). All types of payment cards were affected. Maria Elfvelin, media relations manager at ICA, stated that the problem was due to a leap day bug in their software. It has since been resolved.
  • Sophos, a cybersecurity software vendor, issued an advisory that its products Sophos Endpoint, Sophos Server, and Sophos Home may experience an issue related to SSL certificates if the software is booted on February 29th. As a workaround, they originally suggested to manually disable the feature of their software that decrypts SSL/TLS (HTTPS) connections. Later, a policy update was applied that disabled the feature automatically.
    • At least one report of this indicated that the effect was a certificate validation error message on all outbound web requests. Their entire office was affected.
    • It's unclear if the feature has since been automatically turned back on or not.

Medium Impact

  • Street lighting in Paris, France was inadvertently turned off at midnight at the start of February 29th, according to reporting by Le Parisien, a French daily newspaper. The operator, Cielis, told the reporter that the problem was linked to a programming fault related to the leap day. It took several hours for lighting to be manually restored.
  • Fastrack FS1 smart watches appear to have problems displaying the date and time on February 29th. There have been several reports (1, 2, 3, 4, 5, 6, 7) describing or showing watches frozen at 11:59 PM on Feb 28, and a few other problems, likely related. Fastrack has acknowledged the issue and stated they are working on a fix.
  • Smart watches from Amazfit also had problems dealing with the leap day, either freezing or showing an incorrect date and time. Reports: 1, 2, 3
  • Citrix issued a support article showing that the Citrix HDX HTML5 video redirection service crashes on February 29th. The suggested workaround is to set the computer's calendar date to March 1st, but this can cause other side effects. The issue also affects features related to a Microsoft Teams integration. According to another tweet, a private fix is now available but you must call support to get it.
  • Coreboot, an open source firmware project, had a leap year bug that caused its realtime clock (RTC) date to be incorrect. The issue has been fixed and merged into the code base, but not before it could affect its downstream projects - including this bug in Dasharo, and this bug in Heads.
  • Reportedly, computer systems that issue drivers licenses in parts of Japan had trouble operating on February 29th, according to reporting by The Japan News and BNN Breaking News.
  • Details are scarce, but according to a post on Hacker News, an application related to creating marriage certificates had a bug where it subtracted a value from the year of an applicant's birth date to determine whether they were old enough to marry. The legal minimum age to get married in China is 20 for women and 22 for men. 2004-02-29 is a valid date, but 2002-02-29 is not.

Low Impact

  • The financial services API suite Teller suffered a leap year bug in their certificate generation code, as reported by their CEO. Code sample included! The effect was that new accounts that signed up for Teller were not able to download a required certificate to use the service, until the bug was resolved.
  • Phoenix Framework, a web development platform based on the Elixir programming language, had a problem related to certificate generation. When run on 2024-02-29, its phx.gen.cert task attempted to create a certificate with an invalid expiration date of 2025-02-29. A fix for the issue has been created, and should be included in the next release to prevent the problem from occurring again next leap year.
  • Several different video games had reports of being unplayable on February 29th. The suggested workaround was to take the device offline and adjust its clock to a different date - or simply not play at all.
  • Best Buy, a leading electronics retailer, has an issue on their web site with the drop-down selections used for a credit card's expiration date. As reported in the comments section below, the credit card input form at did not support selecting February 2024 as an expiration date during the leap day. Since credit card expiration dates are valid-through dates, the form should not have disallowed a card expiring in February until March 1st. (Note: I was able to verify this independently.)
  • The open source Akami Unified Log Streamer (ULS) has an open issue that displays a gap in the graph of daily activity where February 29th should be. The issue is also reported for the CLI of Akamai's Secure Internet Access (SIA) Enterprise product, previously known as Enterprise Threat Protector (ETP).
  • The Apple Weather app has a very tiny leap year bug, as reported on Twitter. On February 29th, it reports the 30-day average precipitation is zero, regardless of location. Consequently, the daily amount is miscalculated as well. For example, in my area, it says the precipitation today has been 4.4", it then it reports that is also +4.4" above the 30 day average of 0". (Note: I was able to verify this independently.)
  • The "On This Day" feature within the photos section of Microsoft OneDrive reportedly (1, 2) didn't show photos from February 29th of previous leap years, but rather it was stuck on February 28th.
  • An open source home automation software component related to waste automation schedules encountered a leap year bug in their Python code.
  • The open source COSMIA ACCESS-OM3 global ocean-sea ice-wave coupled model encountered a leap day bug, which appears to be related to another bug in the CMEPS component (Community Mediator for Earth Prediction Systems). The impact of this bug is likely constrained to the scientific data analysis usage that this model is designed for.
  • A person posted to Hacker News stating that they were unable to purchase a YouTube Premium subscription, because the age validation logic thought they were under 18 since they were born on a leap day.
  • A Redditor shared that the popular budgeting app YNAB ("You Need a Budget") had a bug with its feature for tracking recurring scheduled transactions that recur on the last day of a month. Reportedly, this month they all occurred on February 28th instead of February 29th.
  • Reportedly (1, 2), Hesai LiDAR units had a bug related to the leap day, which has been addressed via firmware update. Shanghai-based Hesai was quick to note that the bug was limited to the older L4 units, and was not present in the newer AT128 model presently in use by passenger vehicles.
  • Depending on how you ask it, OpenAI's ChatGPT 3.5 doesn't quite understand whether 2024-02-29 is a valid date or not. At least one user of the OpenAI API encounter failures in their own application due to this issue.
  • As reported in the comments section below, Remind, the popular open source command-line scheduling tool has had an issue handling leap days since near its inception 28 years ago. It's author posted about the bug recently on their mailing list. The bug has been fixed and released today in the latest version 04.03.00.
  • The Android app for BVG, the Berlin public transport company, issued a warning to its users that trips on February 29th appear under February 28th within the app. Reports: 1, 2
  • The official mobile app for Irish Rail (public rail transit in Ireland) was not able to show any routes on February 29th. The issue was acknowledged, redirecting passengers to use their website instead.
  • One person tweeted that Avianca airlines of Colombia printed tickets (or perhaps boarding passes) for February 29th were incorrectly given a March 1st date instead. They included a screenshot of an email they received from Avianca asking them to download their boarding pass again.
  • The specific software is unclear, but here's an interesting find of a leap year bug in software at an eye doctor's office producing two different expiration dates within the same application, due to the leap day.

Unknown Impact

  • A few different people mentioned that they experienced leap day bugs in their own code at various companies. Some included examples of their code, which I greatly appreciate! Reports: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10
  • The programming language Odin had a bug in its datetime_to_time function, which results in March 1st, 2024 incorrectly being coerced to February 29th, 2024. According to its maintainer in the comments below, the problem has been fixed in the latest commit, and will be included in the next monthly release dev-2024-03.
  • The open source network operating system SONiC, a Linux Foundation project, appeared to be suffering build failures with its Azure Pipelines builds during a reboot test. (I'm unable to ascertain the full impact, but the bug appears to have been constrained to the build system, not the product itself.)

Unconfirmed / Coincidently Timed

  • The City of Zürich, Switzerland, paid all of it's employees twice their regular amount for the month of February, as reported by the city itself and several news sources (1, 2, 3). Employees will have to pay the extra amount back. It was originally stated that the problem was due to a technical processing at Zürcher Kantonalbank (ZKB), but later was blamed on software used by Swisscom.
    • Note: I would move this to the "Highest Impact" section, however, it's still unclear if the issue was directly related to the leap day or just coincidentally timed. Note that the payroll date was February 26th, so the issue occurred well before leap day. It's plausible that the culprit was a leap day bug, but not confirmed. If anyone has more details about this one, please let me know!
  • Cloudflare experienced an incident with billing-related services on February 29th, 2024, beginning around 02:00 UTC. It's currently unclear if this incident was caused by a leap year bug or just coincidently timed. While the scope of the incident is unclear, a person on Hacker News posted that they received an invoice with the date 1970-01-01 (the date of the Unix epoch) in the file name where it should have been 2024-02-29. However, the contents of the invoice appeared to be correct.
  • The Innisfail Hospital in Cairns, Queensland, Australia experienced a total outage of its telephone systems on February 29th, as reported on Twitter. This might be related to a leap year bug, or could just be coincidentally timed.

Maybe Not a Bug

  • Confusing, but perhaps by design, an event scheduled in Apple's Calendar app for February 29th that repeats "every year" actually only happens on leap years. It should be pointed out that Google Calendar does the same thing - it just uses a better phrasing: "annually on February 29th".

Got some that aren't in my list? Please let me know and I'll add them! See my About the Author page for contact info, or just comment below. Thanks!

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