Why Do Websites Crash When Busy

As a computer scientist seeing technology advances so much, it is interesting that websites crashing is still seen as normal.

In July 2007, Netflix had an 18 hours blackout preventing any user entering. Even the government hosted Healthcare.gov crashed due to unexpected traffics from enrollments at its start.

So why do websites crash when busy? Websites have limited resources (to save costs) and crash when it failed to handle too many requests. The wеbѕіtеs' hardware either automatically shut-down to prevent overheating leading to unavailability or eventually crashes due to hardware issues. 

healthgov website crash

6 Common Reasons Websites Crash When Too Busy

Having a wеbѕіtе is now mandatory regardless of how small the business. Few folks have thе уеllоw раgеѕ around аnу mоrе аnd аrе lооkіng to fіnd lосаl businesses оn thеіr smartphone, iPad, аnd lарtор.

If уоur buѕіnеѕѕ doesn't hаvе аn оnlіnе hоmе thеn уоu'rе lоѕіng vаluаblе potential income. In my еxреrіеnсе as a Computer Scientist, buѕіnеѕѕеѕ ѕtrugglе with these 3 common problems that cause their website to crash.

#1 Website Built Using Dedicated Servers or Overloaded Shared Servers Instead of Cloud Services

Unlike cloud services like Amazon, Google, dedicated servers or overloaded shared servers can easily crash websites. This is because they were not built to scale. This is a common issue for small-medium businesses.

Website owners loved to use them because the cost is predictable and will not spike up during authorized or unauthorized traffics (such as Distributed Denial-of-Service).

When the traffic spike unexpectedly due to paid promotions or random celebrity's sharing, the website will start to slow down and eventually crash. 

Even using an online website builder (like Wix, Weebly) has limits to their traffic unless you signed up for their Unlimited premium plans.


Without anyone to restart the servers or increase the bandwidth, the website becomes unavailable until everyone gives up.

#2 Lack of Security such as Web Application Firewall (WAF)

Even if you host your website on cloud services, it is still possible to fail to a massive attack. Companies such as KrebsonSecurity that research and report attackers are a common target.

Security companies such as Cloudflare provides an easy way for websites to have protection. They consistently update their algorithm to prevent attackers from bypassing their WAF like an anti-virus.

However, an incorrect setup by administrators exposing their websites could also lead to the bypass of WAF. Usually, security is the last concern of an website developers given the time and cost constraints.

There are even automated tools that script kiddies can use to recon, and attack websites once they bypass the WAF. There are also websites with bounty or services to attack websites. Much of this used to be in Silk Road but scattered across the dark web nowadays.

Ransomware also encrypts and deletes the content of the website or put up advertisements or malware on the website. 

Once an insecure website is attacked successfully, the website either leak information or crash depending on the attacker's motive.

#3: Hosting Videos or Not Compressing Image Sizes

An easy mistake in websites is to host your videos (e.g. corporate videos, product videos) using your own servers. It seems fine when you tested it.

However, once you promote it and thousands of users watch the same videos, the bandwidth will spike up beyond expectations.  Imagine the server as a waiter having to serve 1000x more person than usual.

Either you have to pay a huge sum for cloud computing or the websites just crash.

#4 Website Custom Built By an Inexperienced Website Designer

If you have a bespoke system instead of a website builder used by many, your designer will have to build each component one by one. This includes reading users' input, validating the user's input, and outputting data to users.

While it sounds easy, a custom-built website is a recipe for disaster. Even WordPress, the most popular tools used to build websites have to be upgraded several times a year to prevent errors or loopholes. 

A custom-built website that is not maintained will eventually become obsolete and vulnerable and crashes easily. This issue will be accelerated by using an inexperienced website designer to pull off quick fixes and leading to new issues. 

Hence, websites will crash due to performance issues or coding logic errors.

#5 Websites 3rd Party Plugins Error

The bad news is that even if you used WordPress and updated it frequently, every single plugin is a point of failure. An incorrect coding in the plugin can consume more resources than required (e.g. endless loop pulling data) leading to the website to crash. 

Given website speed is important to users, it is also not recommended to install too many 3rd party plugins, as no one would test their performance and interoperability ... until the website crash.

Hence, websites will crash due to performance issues or coding issues from interoperating with incompatible plugins.

#6 Domain Name Server (DNS) Down

This is one of the least expected reasons for a server to be down. The DNS is pertinent to resolving website names and part of Internet  Service Providers instead of the website owners.

In the past, DNS was just a cost to Internet Service Provider and not well maintained. This was why attacks such as DNS poisoning happened and you get redirected to a fake website and leaking your personal data. 

Nowadays, DNS is better secured but they are still a point of failure (even though each provider gives 2 servers to prevent any downtime. Nevertheless, big companies such as Google ( and Cloudflare ( also came up with their own DNS services. The reason for providing the free DNS service (claiming faster speed) is probably to collect more data on the websites people used.

Hence, websites will seem to crash or become unavailable for a computer with broken DNS.


In summary, performance, security, and human coding issues can cause website to crash. These issues usually surface when it is busy or overloaded beyond its normal operating conditions. I don't foresee any solutions given websites don't mind crashing as long as there is no data loss and website crashes are usually recoverable.


Efforts have been made to get the information as accurate and updated as possible. If you found any incorrect information with credible source, please send it via the contact us form
Author: Sky Hoon
Website Builder. He has a Bachelor Degree in Computer Science and loved to use technology to solve the world's issue, one at a time. For now, trying to blog for a living.
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