This issue sometime may occur because new SharePoint subscription Grant App Permission is disabled by default.
To enable it, please run the following commands in Windows PowerShell:
- Install-Module -Name Microsoft.Online.SharePoint.PowerShell
- $adminUPN=”(the full email address of a SharePoint administrator account, example: email@example.com)”
- $orgName=”(name of your Office 365 organization, example: contosotoycompany)”
- $userCredential = Get-Credential -UserName $adminUPN -Message “pwd”
- Connect-SPOService -Url https://$orgName-admin.sharepoint.com -Credential $userCredential
- set-spotenant -DisableCustomAppAuthentication $false
Note : Fill in the values for the $adminUPN and $orgName variables (replacing all the text between the quotes, including the characters), and then run the following commands in the Windows PowerShell. When prompted with the Windows PowerShell credential request dialog box, type the password for the SharePoint admin account.
Let us know at firstname.lastname@example.org if you have any concerns or other questions. We will be happy to help you.