Slack experienced a possible outage on Wednesday, with more than 2,800 users reporting problems with the platform by 3:54 p.m. PT.
Most of those users said they could not send or receive messages. The number of reports rose through the day: later on Wednesday more than 3,400 users reported an issue, and still later more than 6,000 users had reported problems with the platform.
Reports of a slack down began to climb as governments, companies and individual users found teams unable to exchange messages. A little before 11.30pm local time on Wednesday, May 28, users in the UK, US and Australia reported problems; shortly before 11.45pm at least 36 reports came from UK-based users.
Downdetector tracks outages by collecting status reports from multiple sources, and it showed a steady rise in problem reports that matched the numbers logged through the afternoon and evening.
Slack's public status page initially showed no issue but later updated to say, "Severe Latency Impacting All Slack Services." An incident report from Slack said the Slack Engineering team was investigating severe latency impacting all Slack services. The company apologized for any inconvenience the issue was causing and said it would provide an update as soon as it had more information to share.
The timeline contains an uncomfortable gap: early in the disruption Slack's status page listed no problem while thousands of users were already reporting failures. That disparity — between visible user reports and the platform's initial page state — left some teams working blind as the volume of reports rose from the low thousands to more than 6,000.
Most users described the same basic symptom: messages failing to send or not arriving. Slack framed the incident as a latency problem across services rather than a narrow feature outage, and its engineering team was cited as investigating that severe latency.
The immediate question for organizations that rely on the platform is simple and pressing: when will message delivery return to normal, and when will Slack explain what caused the widespread interruptions? Slack said it would provide an update as soon as it had more information to share, leaving the timing and technical details unresolved for now.
