Top 5 Black Friday Website Crashes and How to Avoid Them
Black Friday is the only peak in the IT calendar that we know years in advance. The date is fixed, the marketing plan is approved months ahead, and every retailer expects record traffic. Yet every year, well-known brands greet customers with error pages, waiting screens, and broken checkouts.
In the past, a slow website was an inconvenience. Today, a few hours of downtime on Black Friday or Cyber Monday can cost millions in sales, push loyal customers to competitors, and damage a brand for an entire season. With Black Friday 2026 only three weeks away, we looked back at five of the most visible crashes of the shopping season and what they teach us about performance and reliability.
1. Shopify, Cyber Monday 2025: when login becomes the bottleneck
On Cyber Monday 2025, merchants started reporting trouble logging in to their Shopify accounts around 6:45 a.m. PT, and many couldn't access their point-of-sale systems or process transactions (TechCrunch). Shopify later identified the cause as an issue with its login authentication flow. Downdetector showed roughly 4,000 problem reports at 11 a.m. ET, and some services were still listed as degraded at 9 p.m. ET (Business Insider). The timing was painful: Shopify had processed $6.2 billion in gross merchandise volume on Black Friday alone, up 25% year over year (Business Insider). What happens when one shared service fails for thousands of merchants at once?
#Lesson: Authentication, payment, and other shared services are often the true single point of failure. They need the same peak load and failure testing as the storefront.
2. Costco, Thanksgiving 2019: 16.5 hours of lost opportunity
Costco.com started showing "intermittent slow loading and transaction times" late on the Wednesday before Thanksgiving, according to Catchpoint, followed by a complete outage early on Thanksgiving Day (CNBC). Downdetector data indicated the site was down for at least 16.5 hours. CFO Richard Galanti said Costco had prepared "plenty of processing capacity," but "there was something that occurred," and admitted the company "did leave something on the table." LovetheSales.com estimated the lost sales at up to $10.9 million (Business Insider).
#Lesson: Enough capacity is not the same as proven capacity. The early warning signs were visible the evening before. Monitoring only helps if someone acts on the signal.
3. Lowe's, Black Friday 2018: a decade-old platform meets modern demand
On Black Friday 2018, Lowe's customers hit a "down for maintenance" page during prime shopping hours (CNBC). The company temporarily shut the site down and relaunched it later that day. CEO Marvin Ellison later explained that the root cause was "very simple": "The entire e-commerce site was a decade old" (Retail Dive). Lowe's moved the site to the cloud to remove its volume limitations, and Ellison said these investments prepared the company for the demand surge during the pandemic two years later.
#Lesson: Technical debt has a breaking point, and peak season is where you find it. A failure can trigger modernization that pays off for years.
4. J.Crew, Black Friday 2018: "Hang on a Sec"
The same Black Friday, J.Crew shoppers saw a "Hang on a Sec" message after the site ran into technical difficulties (CIO Dive). J.Crew said the problems were "due to high demand," and LovetheSales.com estimated the crash could have cost $775,000 in sales (Dayton Daily News). The disruption lasted about five hours (Retail Week). J.Crew was not alone: Walmart, Ulta, and Lululemon shoppers also reported glitches that weekend (CIO Dive).
#Lesson: "High demand" is not a root cause. It is a load level the system was never validated against.
5. Best Buy, Black Friday 2014: the mobile spike
On Black Friday morning 2014, BestBuy.com went offline for about an hour after a concentrated spike in mobile traffic. Best Buy shut the site down "to take proactive measures to restore full performance" (Fortune).
#Lesson: Peak load is not only about volume. The arrival pattern matters. A sudden spike from one channel can break a system that handles the same daily volume without trouble.
What do these crashes have in common?
Looking at all five cases, the patterns are remarkably consistent:
#The peak was known, but the workload was not modeled. Target experienced a similar situation on Cyber Monday 2015, when traffic reached twice its previous busiest day (The Seattle Times). Last year's peak is not a valid forecast.
#The weakest component decided the outcome. Login flows, legacy platforms, and mobile entry points failed while the rest of the system was fine.
#Warning signals came before the crash. Slow response times and rising error rates usually show up hours before a full outage.
How could these crashes have been avoided?
#Build a realistic peak workload model. Use production analytics, marketing campaigns, and growth forecasts to model the expected peak per channel, then test at two to three times that load. Include doorbuster moments when a deal goes live at a fixed time.
#Run spike, stress, and endurance tests, not only load tests. Best Buy showed that sudden bursts break systems. Validate how fast traffic can ramp up, where the breaking point is, and whether the system recovers on its own.
#Test the critical shared services end to end. Authentication, search, cart, payment, inventory, and third-party APIs must be part of the test scope. The Shopify case shows what happens when one shared service fails under pressure.
#Design for graceful degradation. Target kept its site available by metering traffic and queuing guests during spikes (The Seattle Times). Waiting rooms, rate limits, feature toggles, and circuit breakers keep customers buying when demand exceeds capacity.
#Make observability actionable. Full-stack observability with Dynatrace, real user monitoring, and synthetic checks on the checkout journey detects degradation before customers notice. Define clear thresholds, alerts, and owners for the peak days.
#Freeze changes and rehearse the incident. Enforce a code freeze ahead of the peak, prepare runbooks, rehearse failover, and staff a war room with decision makers who can act within minutes.
#Retire technical debt before it retires you. Lowe's proved that a legacy platform eventually hits its limits. Modernization, autoscaling, and capacity validation are business investments, not IT luxuries.
Performance is a matter for everyone
Black Friday crashes are rarely caused by bad luck. They result from untested assumptions about load, capacity, and dependencies. The good news is that every one of these failures was predictable and testable.
Is your platform ready for Black Friday and Cyber Monday 2026?
At Performetriks, we help organizations prove their readiness before the peak. Our Peak Readiness approach combines realistic workload modeling, load, spike, and stress testing with Performator, Dynatrace-based observability, and a clear go-live checklist for your peak days. There are still three weeks left. Contact us at performetriks.com to schedule a Black Friday readiness check and let your customers shop instead of waiting.
Happy Peak Season Testing:)
References:
Business Insider. (2019, December). Costco's CFO said it "left something on the table" after the Thanksgiving website crash. https://www.businessinsider.com/costco-ceo-addresses-thanksgiving-website-crash-stopped-shoppers-2019-12
Business Insider. (2025, December). Shopify experienced instability for hours on one of the busiest shopping days of the year. https://www.businessinsider.com/shopify-was-unstable-for-6-hours-on-busy-cyber-monday-2025-12
CIO Dive. (2018, November 26). Black Friday traffic brings down J. Crew, Ulta sites, among other retailers. https://www.ciodive.com/news/black-friday-traffic-brings-down-j-crew-ulta-sites-among-other-retailers/542926/
CNBC. (2018, November 23). Lowe's website "down for maintenance" on Black Friday. https://www.cnbc.com/2018/11/23/lowes-website-down-for-maintenance-on-black-friday.html
CNBC. (2019, November 29). Costco's website goes down on Thanksgiving, other retailers also see outages Friday. https://www.cnbc.com/2019/11/29/costcos-website-goes-down-on-thanksgiving-others-see-outages.html
Dayton Daily News. (2018, November). Retail websites crash on Black Friday: What to expect today. https://www.daytondailynews.com/business/retail-websites-crash-black-friday-what-expect-today/GE04DSFuxL1hUFdQf1YoJN/
Fortune. (2014, November 28). Best Buy's website goes down on Black Friday. https://fortune.com/2014/11/28/best-buys-website-down/
Retail Dive. How a Black Friday website crash prepped Lowe's for the pandemic. https://www.retaildive.com/news/lowes-ceo-marvin-ellison-black-friday-website-crash-pandemic/641142/
Retail Week. Five lessons for retailers to avoid common seasonal ecommerce mistakes. https://www.retail-week.com/retail-voice/five-lessons-for-retailers-to-avoid-common-seasonal-ecommerce-mistakes/7040593.article
TechCrunch. (2025, December 1). Shopify resolves outage disrupting merchants on Cyber Monday. https://techcrunch.com/2025/12/01/shopify-resolves-outage-disrupting-merchants-on-cyber-monday/
The Seattle Times. (2015, November 30). Target's website locks out some users on Cyber Monday. https://www.seattletimes.com/business/retail/targets-website-locks-out-some-users-on-cyber-monday/
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