Microsoft Teams Outage – Extra.js

On February 18, 2019, Microsoft Teams went down for both web and desktop clients. Mobile apps on iOS and Android were unaffected.

The Cause

The outage was traced to the unavailability of a single JavaScript file:

https://teams.microsoft.com/scripts/extra.js

This file is a dependency for both the web and desktop clients. When it returns a 500 error instead of a 200 OK, the application fails to load. Microsoft's 365 status page confirmed the issue and elevated it to an incident.

Monitoring for Recovery

While waiting for Microsoft to resolve the issue, the following PowerShell script can be used to poll the endpoint and alert you the moment service is restored:

$status = $null
while($status -eq $null){
  try{
    $uri = "https://teams.microsoft.com/scripts/extra.js"
    $status = (Invoke-WebRequest -Uri $uri -UseBasicParsing).StatusCode
  } catch{
    write-host (Get-Date) "Request Failed: $status"
    $status = $null
    sleep -Seconds 5
  }
}
write-host (Get-Date) "Succeeded"

The script polls every five seconds. Once extra.js returns a successful response, it prints the timestamp and exits — your cue to reconnect.