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On a normal Tuesday morning, a single faulty update, a mistyped configuration or a failed cloud region can stop a business in its tracks. Orders stall, phones go quiet and teams sit waiting for systems to come back. For most organizations, the question isn’t whether downtime will happen. It’s what will cause it and how long it will last.
The good news is that business downtime causes are well understood. Most of the incidents businesses face come from cyberattacks, human error, third-party and cloud outages, faulty updates, power and network failures, hardware faults, traffic surges, configuration mistakes or natural disasters. What has changed is where those failures start. Many of the most disruptive outages of the past two years began outside the affected companies entirely, in a cloud provider, a security vendor or an internet service, before spreading to thousands of businesses at once.
This guide walks through the major business downtime causes one by one: what each looks like, what it costs, real incidents from 2024 and 2025, and the prevention steps that make the biggest difference. It’s written for IT leaders, operations managers and executives across North America who want a clear view of their exposure and a practical plan to reduce it.
What Counts as Business Downtime?
Business downtime is any period when the systems, applications or services a business depends on are unavailable, or too degraded to use. It comes in three forms:
- Unplanned outages: systems fail unexpectedly, from a crashed server to a regional cloud failure.
- Degraded performance: systems stay online but are so slow or error-prone that work effectively stops.
- Planned downtime: scheduled maintenance windows, which become a problem when they overrun or are poorly timed.
This guide focuses on unplanned outages and degraded performance, because those are the events that catch businesses unprepared.
What Downtime Costs
Before looking at individual business downtime causes, it helps to understand the stakes. Downtime is no longer a minor IT inconvenience. Research across large and mid-sized organizations shows how expensive it has become:
- Downtime costs Global 2000 companies $400 billion a year, or 9% of profits (Splunk and Oxford Economics).
- 97% of large enterprises say a single hour of downtime costs more than $100,000. 41% put the hourly cost between $1 million and more than $5 million (ITIC 2024).
- 57% of respondents to Uptime Institute’s 2025 survey said their most recent major outage cost more than $100,000, and 1 in 5 said it cost more than $1 million (Uptime Institute).
How to estimate your own cost per hour
Most organizations underestimate downtime because they only count lost sales. A more realistic estimate adds lost productivity:
Cost per hour = revenue at risk per hour + productivity lost per hour
Example (illustrative): a company with $50 million in annual revenue sells around the clock. It has 200 employees at an average loaded cost of $50 per hour, and an outage idles half of them.
- Revenue at risk: $50,000,000 ÷ 8,760 hours = $5,708 per hour
- Productivity lost: 200 × $50 × 50% = $5,000 per hour
- Total: $10,708 per hour
A four-hour outage would cost this business about $42,832. That’s before recovery work, penalties, overtime or reputational damage.
The 10 Most Common Business Downtime Causes at a Glance
# | Cause | What it looks like | Primary prevention |
1 | Cyberattacks and ransomware | Encrypted systems, locked accounts, stolen data | 24/7 monitoring, MFA, tested immutable backups |
2 | Human error and failed changes | A bad configuration push, a deleted resource, a skipped procedure | Change control, peer review, rollback plans |
3 | Third-party and cloud outages | A cloud region, SaaS platform or vendor goes down | Multi-zone design, dependency mapping, fallbacks |
4 | Faulty software updates | A routine update crashes systems at scale | Staged rollouts, update testing, rollback |
5 | Power failures | Grid loss, UPS or generator failure | Redundant power, regular failover testing |
6 | Network and connectivity failures | Fibre cuts, ISP outages, DNS problems | Redundant links, diverse carriers, monitoring |
7 | Hardware failure | Failed drives, servers or network devices | Redundancy, lifecycle management, monitoring |
8 | DDoS attacks and traffic surges | Websites and apps overwhelmed by traffic | DDoS protection, auto-scaling, capacity planning |
9 | Configuration drift and expired certificates | Services break after silent changes or an expired certificate | Infrastructure as code, certificate monitoring |
10 | Natural disasters and facility events | Floods, storms, fires, cooling failures | Geographic redundancy, disaster recovery plans |
1. Cyberattacks and Ransomware
Security incidents are the largest source of downtime for large organizations. Splunk found that 56% of downtime incidents stem from security incidents such as phishing. The remaining 44% were caused by application or infrastructure issues.
Ransomware is the most disruptive form. In Veeam’s 2025 research, 69% of organizations had been hit by ransomware in the previous 12 months. Only 10% of those attacked recovered more than 90% of their data (Veeam).
Attackers are also faster than ever. Mandiant’s M-Trends 2026 report found that exploiting vulnerabilities was the top way attackers got in for the sixth year running, at 32% of intrusions. The median time for an initial access group to hand access to a second threat group fell to 22 seconds (Google Cloud, M-Trends 2026).
How to prevent it:
- Around-the-clock threat monitoring
- Multi-factor authentication on every account
- Fast patching of internet-facing systems
Immutable backups, restored on a schedule to prove they work
2. Human Error and Failed Changes
Splunk’s research named human error the number one cause of downtime. Uptime Institute’s 2026 analysis adds an important detail: failing to follow established procedures remains the leading driver of human error-related outages, alongside unclear processes and installation errors.
Human error rarely looks dramatic. It’s a firewall rule pushed to the wrong environment, a database permission changed without review, or a maintenance step skipped under time pressure.
How to prevent it:
- Formal change control
- Peer review of risky changes
- Documented runbooks
A tested rollback plan for every significant change
3. Third-Party, Cloud and SaaS Outages
Uptime Institute has tracked publicly reported outages for nine years. Over that time, about two-thirds were caused by third-party IT and data center providers, including cloud, internet, telecom and colocation companies.
The October 2025 AWS outage shows why. A timing bug in DynamoDB’s DNS management system left the service’s DNS record in the US-East-1 region empty, and automation failed to repair it. The failure cascaded to EC2 instance launches, Lambda and other services, and some customers reported issues for up to 15 hours (InfoQ).
How to prevent it:
You can’t stop a vendor from failing, but you can limit the damage:
- Deploy critical workloads across multiple availability zones.
- Map every critical dependency.
Document manual fallbacks for the vendors you rely on most.
4. Faulty Software Updates
On July 19, 2024, a faulty update to CrowdStrike’s security software crashed about 8.5 million Windows devices, less than 1% of all Windows machines (TechCrunch). Airlines, hospitals and banks were disrupted worldwide. Cyber insurer Parametrix estimated losses of about $5.4 billion across the Fortune 500, with only 10% to 20% of that insured (Axios).
The lesson is uncomfortable: a routine update from a trusted vendor can cause more disruption than many cyberattacks.
How to prevent it:
- Staged rollouts that test updates on a small group first
- Controls over how and when vendors can push updates
A rehearsed recovery procedure for failures across many devices at once
5. Power Failures
According to Uptime Institute, power remains the leading cause of impactful data center outages. The main failure points are uninterruptible power supplies (UPS), transfer switches and generators.
The risk can be higher for businesses running their own server rooms, if backup power isn’t tested and maintained to the same standard as in professional facilities.
How to prevent it:
- Redundant power paths
- Regular load testing of UPS systems and generators
Moving critical workloads to facilities or cloud regions with proven power resilience
6. Network and Connectivity Failures
Uptime Institute reports that outages linked to fibre and connectivity issues are rising, and that they’re more likely to cause extended disruptions. A single severed fibre line or ISP failure can cut off an office, a warehouse or an entire region.
How to prevent it:
- Redundant internet links from different carriers
- SD-WAN, which switches automatically between connections when one fails
Continuous monitoring of network performance across every site
7. Hardware Failure
Hardware is more reliable than it used to be, but it still fails. Backblaze tracks more than 340,000 drives. It reported an annualized failure rate of 1.36% in 2025, down from 1.55% in 2024 (Backblaze).
At that rate, an environment with 500 drives should expect:
500 × 1.36% = about 7 drive failures a year
Without redundancy, each failure is a potential outage.
How to prevent it:
- RAID and redundant storage
- Proactive hardware health monitoring
- Lifecycle management that replaces equipment before it reaches end of support
8. DDoS Attacks and Traffic Surges
Distributed denial-of-service (DDoS) attacks flood websites and applications with traffic until they stop responding. Cloudflare mitigated 18.2 million network-layer DDoS attacks in the third quarter of 2026 alone, or about 8,226 every hour. 96% of those attacks ended in under 10 minutes (Cloudflare). Attacks that short are over before most people could respond by hand, which is why automated, always-on protection matters.
Legitimate traffic can have the same result. A product launch, a viral campaign or a seasonal peak can overwhelm infrastructure that wasn’t built to scale.
How to prevent it:
- Always-on DDoS protection
- Auto-scaling infrastructure
Load testing before major events
9. Configuration Drift and Expired Certificates
Some outages have no dramatic cause at all. A server’s configuration slowly drifts from its documented state, or an SSL/TLS certificate expires unnoticed, and services stop working.
Small configuration changes can also have large effects. Cloudflare’s November 18, 2025 outage began with a database permissions change. That change made a bot management feature file grow from about 60 features to more than 200, which exceeded a hard-coded limit in Cloudflare’s core proxy. Errors spread across services that depend on Cloudflare until a fix was deployed about three hours later (ThousandEyes).
How to prevent it:
- Infrastructure as code, so environments match their definitions
- Automated certificate monitoring and renewal
Validation checks on configuration files before they’re deployed
10. Natural Disasters and Facility Events
Floods, storms, wildfires, cooling failures and building incidents can take an entire location offline. For a business with a single office or server room, one local event can stop everything.
How to prevent it:
- Geographic redundancy for critical systems
- Offsite and cloud backups
- A disaster recovery plan with clear recovery time and recovery point objectives (RTO and RPO), tested at least once a year
Recent Major Outages and What They Teach
Date | Incident | Root cause category | Lesson for businesses |
July 19, 2024 | CrowdStrike update crashes about 8.5 million Windows devices | Faulty software update | Control how vendor updates reach your systems |
October 19 to 20, 2025 | AWS US-East-1 outage | Third-party cloud (DNS automation fault) | Avoid relying on a single region for critical workloads |
November 18, 2025 | Cloudflare global outage | Configuration change | Validate configuration files before deployment |
These incidents span three different business downtime causes but share a pattern: the customers affected didn’t cause them. Their exposure came from dependencies they didn’t control.
How to Measure Downtime
You can’t reduce what you don’t measure. Four metrics matter most:
- Availability: the percentage of time a system is usable
- Mean time to detect (MTTD): how long it takes to notice a problem
- Mean time to resolve (MTTR): how long it takes to restore service
- Incident frequency: how often outages occur, broken down by cause
Small differences in availability add up quickly over a year of 8,760 hours. Our guide to always-on IT operations covers uptime targets in more depth.
- 99.9% availability: 8,760 × 0.1% = 8.76 hours of downtime per year
- 99.99% availability: 8,760 × 0.01% = about 53 minutes per year
Tracking incidents against the 10 business downtime causes in this guide shows where prevention spending will have the biggest effect.
When Downtime Becomes a Reportable Incident
If an outage involves a security breach, it may trigger legal reporting obligations:
- Canada: under PIPEDA, breaches that create a real risk of significant harm must be reported to the Office of the Privacy Commissioner and to affected individuals. Records of every breach must be kept for two years (OPC).
- United States: financial institutions under FTC jurisdiction must report breaches that expose the unencrypted information of at least 500 consumers. The deadline is 30 days after discovery (Federal Register).
Fast detection and good incident records aren’t just operational goals. They’re compliance requirements.
A Practical Prevention Checklist
- Map your critical systems and the vendors, cloud services and networks each one depends on.
- Estimate your cost per hour using the formula above, so investment decisions are grounded in numbers.
- Monitor around the clock, covering infrastructure, security and third-party service health.
- Control every change, with peer review and a rollback plan.
- Stage software updates, including those pushed by security and infrastructure vendors.
- Build redundancy into power, network, storage and cloud deployments.
- Back up immutably and test restores on a schedule.
- Set and test recovery targets, with a defined RTO and RPO for each critical system.
- Track incidents by cause and review the trends every quarter.
How Zazz Helps Reduce Downtime
Zazz is a managed IT and cybersecurity partner for organizations with 20 to 500 employees, supporting 100+ businesses across North America (Zazz Managed IT Services). Its model is built around the causes in this guide:
- 24/7 monitoring: a round-the-clock network operations centre and help desk that catch warning signs before they become outages.
- Fast response: an average first response under 10 minutes for critical issues, plus 24/7 emergency support.
- Backup and disaster recovery: managed backup and recovery, including Microsoft 365 and Google Workspace data.
- Managed cybersecurity: incident response led by a security operations team, to contain threats quickly.
- Certified operations: an ISO 27001 and SOC 2 Type II certified team, working within an ITIL-aligned framework.
- One accountable owner: a dedicated Delivery Manager for every client, with monthly reports on uptime, patching and SLA compliance, plus quarterly strategic reviews.
- Quick start: onboarding begins within 5 to 7 business days, and most mid-sized clients are fully moved over in 2 to 4 weeks.
Frequently asked questions
What are the most common causes of business downtime?
The most common business downtime causes are:
- Cyberattacks and ransomware
- Human error and failed changes
- Third-party and cloud outages
- Faulty software updates
- Power failures
- Network failures
- Hardware failure
- DDoS attacks
- Configuration problems
- Natural disasters
What is the number one cause of IT downtime?
Splunk’s research identifies human error as the number one cause of downtime. Security incidents account for 56% of downtime incidents at large organizations. In data centers, Uptime Institute reports power as the leading cause of impactful outages.
How much does an hour of downtime cost?
It varies by business, but 97% of large enterprises say an hour costs more than $100,000. To estimate your own figure, add the revenue at risk per hour to the productivity lost per hour.
How can businesses prevent downtime?
Combine these measures:
- 24/7 monitoring
- Change control
- Staged updates
- Redundancy in power, network and cloud
- Tested backups
- A disaster recovery plan with defined recovery targets
How much do managed IT services cost for a fintech startup?
No. Cloud providers fail too, as the October 2025 AWS outage showed. Spreading critical workloads across multiple availability zones and planning fallbacks reduces the impact.
Turn Downtime Causes Into a Prevention Plan
Every business faces the same core business downtime causes. What separates a minor disruption from a costly outage is how quickly problems are detected, how well changes are controlled and how thoroughly recovery has been tested. For a clear picture of where your environment is most exposed, book a free 30-minute review with Zazz to assess your monitoring, backup and recovery readiness.
