Cloudflare outage cause revealed: This is what happened.

UPDATE Tuesday, Nov. 18, 11:27 a.m. ET: Cloudflare confirmed it experienced a "significant outage" on Tuesday that stemmed from a crash in a software system that handles traffic for a number of its services.

The company wrote in an emailed statement to Mashable that the issue had been fully resolved and added that it did not appear to be an attack or caused by malicious activity.

The statement from Cloudflare read:

"Many of Cloudflare's services experienced a significant outage today beginning around 11:20 UTC. It was fully resolved at 14:30 UTC. The root cause of the outage was a configuration file that is automatically generated to manage threat traffic. The file grew beyond an expected size of entries and triggered a crash in the software system that handles traffic for a number of Cloudflare's services.

To be clear, there is no evidence that this was the result of an attack or caused by malicious activity. We expect that some Cloudflare services will be briefly degraded as traffic naturally spikes post incident but we expect all services to return to normal in the next few hours. A detailed explanation will be posted soon on blog.cloudflare.com. Given the importance of Cloudflare's services, any outage is unacceptable. We apologize to our customers and the Internet in general for letting you down today. We will learn from today's incident and improve."

Issues with Cloudflare — one of the internet's major infrastructure providers — led to massive outages Tuesday morning as East Coast folks logged on to work. We're now starting to get answers as to why that happened.

Cloudflare emailed a statement to Mashable, suggesting that unusual, heavy traffic to its services was to blame. The company has not yet stated whether the unusual traffic appears to be of a nefarious nature.

Read the statement from Cloudflare:

"We saw a spike in unusual traffic to one of Cloudflare's services beginning at 11:20 UTC. That caused some traffic passing through Cloudflare's network to experience errors. We do not yet know the cause of the spike in unusual traffic. We are all hands on deck to make sure all traffic is served without errors. After that, we will turn our attention to investigating the cause of the unusual spike in traffic. We will post updates to cloudflarestatus.com and more in-depth analysis when it is ready to blog.cloudflare.com."

That spike in unusual traffic, it seems, sparked the massive issues on Tuesday. The list of services experiencing outages was vast, but appeared to include heavy hitters like OpenAI, X, Grindr, and many more. Pretty much anyone with an internet connection would be affected by a Cloudflare outage. User-reported issues on Downdetector continued to spike as we neared 10 a.m. ET, indicating the problems persisted. (Disclosure: Downdetector is owned by Ziff Davis, the same parent company as Mashable.)

"We've deployed a change which has restored dashboard services. We are still working to remediate broad application services impact," read the most recent update on Cloudflare's status page.

Like the recent AWS outage, Cloudflare is one of the major pillars of the internet. When it goes down, the downstream effects are serious and vast — as we're seeing Tuesday.