Outlook REST APIs calls failed - Missing Access-Control-Allow-Origin header? RRS feed

  • Question

  • Hi Guys,

    I've been facing an issue with failed Outlook REST APIs calls since yesterday 26-Jul. It was working fine before that.

    It seems the APIs are not returning Access-Control-Allow-Origin header which cause preflight request in Chrome failed. API calls are originated from SharePoint Online with the token getting with ADAL.js.

    Error in Chrome's console:

    Failed to load$select=*&$top=1000&Status!=Completed&$filter=Status%20ne%20%27Completed%27&$orderby=DueDateTime/DateTime%20asc: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '' is therefore not allowed access. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.

    Please let me know if you have any ideas on this.

    Thanks & Best Regards,


    Friday, July 27, 2018 3:07 AM

All replies

  • Hello Hung,

    This forum(Outlook for Developers) is for discussing development issue related to Outlook Object Model and I think your issue is more related to Office 365 development. So I will move the thread to Office 365 for Developers forum.

    Thanks for understanding,

    Best Regards,


    MSDN Community Support
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    Monday, July 30, 2018 1:18 AM