Today, for the first time, I'm continually getting Error occurred in deployment step 'Install SharePoint Add-in': The remote server returned an error: (429) while trying to side-load a Add-in to my SharePoint online development site. I tried on two different dev sites and get the same thing: periodically the server returns 429. I'm the only one on the entire tenant. Both dev sites have 300 server resources and I have not seen this error before today, having developed with this site for more than 2 years.

Anyone else seeing this today or know if there's anything I can try on my end? I can't imagine I'm being throttled for too much traffic since the add-in packaged is only 200KB and I'm uploading it only every 5-10 minutes, and my behavior is no different from how it's been the last two years working with the site...

1 Answer 1


Try Set-SPOTenant -LegacyAuthProtocolsEnabled $True

After connecting to your tenant with Connect-SPOService -Url https://<yourtenant>-admin.sharepoint.com

  • 1
    Update: I was having the same issue and while I found this seemed to work initially, the problem came back. Feb 15, 2018 at 2:35

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