Slack explains last week's hours-long outage

Slack had a lot of glitches when its servers went down.

Corinne Reichert Senior Editor
Corinne Reichert (she/her) grew up in Sydney, Australia and moved to California in 2019. She holds degrees in law and communications, and currently writes news, analysis and features for CNET across the topics of electric vehicles, broadband networks, mobile devices, big tech, artificial intelligence, home technology and entertainment. In her spare time, she watches soccer games and F1 races, and goes to Disneyland as often as possible.
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Corinne Reichert
2 min read

What have you done, Slack?


Work messaging app platform Slack experienced a lot of issues Friday afternoon, the company confirmed on Twitter . Some messages weren't sending and some were taking a lot longer than usual to load.

"Sorry for the trouble! We're working on an incident at the moment, and hope to have everything back to normal as quickly as we can," Slack said in a tweet, pointing to its service status page.

Slack said it eventually repaired the issue at 8:15 p.m. PT Friday, and then on Saturday night it detailed what went wrong.

According to the platform, some of its servers became unavailable at around 1:30 p.m. Friday. This resulted in "degraded performance" for job processing, which caused delays and errors across notifications, message posting and unfurls. There was a 10-25% job error or failure rate during that time, Slack said.

Slack's response team is continuing to investigate the issue, as well as working on preventative measures so it doesn't happen again.

At the time, Slack's service status page acknowledged outages across login/SSO, connections, link previews, notifications, messaging, posts/files, calls, search, apps/integrations/APIs and workspace/org administration. So, everything really.

"Just been a rough day for us today. We're very sorry for any disruption and we're doing our best to get back on track," Slack tweeted.

At 3:56 p.m. Friday, the company said refreshing the Slack app with Cmd/Ctrl + R should bring back connectivity -- but that file uploads still weren't working for some users.

Slack was "still working hard to restore file upload functionality" at 4:54 p.m., adding on Twitter at 5:05 p.m. that its team is "working to make sure this doesn't happen again."

First published at 1:37 p.m. PT on June 28.
Updated at 4:22 p.m. PT: adds update on outage details
Updated at 5:28 p.m. PT: adds update on outage details
Updated on July 1 at 3:11 p.m. PT: adds update on Slack outage explanation; originally published under headline "Slack goes down because of 'connectivity issues'"

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