Cloudflare, the content delivery and cybersecurity provider used by approximately 20% of all websitessays it has resolved the issue that caused a third of its sites to go down early Friday morning. Affected sites include banking sites, the career social media platform LinkedIn and the Virtual Service Service Zoom.

San Francisco-based Clockflase said up to 28% of its sites were down on Dec. 5 at 3:47 a.m. ET, after the company changes in its systemsbut said it fixed the problem within 25 minutes.

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The problem occurred when Cloudflare increases the buffer designed to prevent a critical vulnerability. In order to facilitate the update, the company said that it is moving away from a test tool, and this causes the system to return an error. Repeating the changes fixed the issue.

This is the second one Cloudflare Outage Time in recent weeks. An unrelated change on November 18 brought the company’s services down for hours.

Cloudflare isn’t the only web company experiencing problems recently. STUDY Amazon Web Services Services In October it affected millions of visitors to popular destinations, including reddit, snapchat, forneite, Roblox, Venmo itself.