As of this story, workplace collaboration app Slack was down for an awful lot of people. (GeekWire screnshot)

A major outage took out Slack’s services for what appeared to be a large portion of its userbase Tuesday afternoon.

It’s not immediately clear what caused the outage: Slack acknowledged it was having issues at 3:58pm PDT, but the outage started a few minutes earlier, and it’s still down as of this writing.

Update 5:54pm: GeekWire’s Slack is back up for the first time in almost two hours, but Slack’s status page has yet to be updated with confirmation that it’s back in business.

Update 6:04pm: Sounds like Slack has a handle on whatever caused this outage:

The fixes we’ve rolled out are showing positive results, though we’re not out of the woods yet. Please hold tight as we work to get everyone back into their workspace. 6:01 PM PDT

Update 6:33pm: GeekWire’s Slack is still up, but Slack has removed the update posted above from its status page, which …

Update 6:57pm: Slack still hasn’t updated its status page, but its Status Twitter account seems to have declared an all-clear. Hopefully the company takes advantage of this opportunity to strike a blow for transparency in outage statements.

Slack’s workplace collaboration app is the darling of the tech set, used as a central hub for inter-company communication and coordination by 6 million people every day (including the staff of GeekWire). And in a world where billions of dollars are spent trying to capture the attention of people on the internet, Slack users spend hours each day in its application.

As it happens, yesterday I spoke to Slack’s Julia Grace, director of infrastructure engineering at Slack, preparing for our upcoming session at the Structure cloud conference in San Francisco.

Grace — who is having a bad afternoon — said that Slack has been very careful about how it embraces new enterprise technology because of a healthy fear of causing problems for that dedicated user base. At the same time, Slack has faced classic scaling challenges that have bedeviled all big web services at one point or another; “we’re flying an airplane while rebuilding the engine,” she said. Now we’ll have a few things to talk about at Structure 2017.

We’ll update this post if and when we learn more about what happened. As is usual in these situations, Twitter comedians came out in force.

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