Exchange ErrorInvalidClientAccessTokenRequest
问题 I built an Outlook Add-in and it uses a token to download email attachments from the Exchange server. On my O365 developer account, it successfully retrieves the token. The Add-in has been deployed to the client's Outlook but when they try to retrieve the token, this is the response message: MessageText:"The token for this extension could not be retrieved. "ResponseClass:"Error" ResponseCode:"ErrorInvalidClientAccessTokenRequest" Token:null __type:"GetClientAccessTokenResponseMessage: