Adding a Team using Microsoft Graph API, App vs. Delegated Permissions
We discovered an interesting issue when trying to create a team via the 1.0 Graph API as described in this article: https://docs.microsoft.com/en-us/graph/teams-create-group-and-team. We were using and access token with Application Permissions for Group.ReadWrite.All to create the group and then add the team to the group. We need to use Application Permissions in order to create more than 250 groups without requiring a Global Admin account. We are able to successfully create the new team, but were always getting the "Cannot retrieve files" message when clicking on the Files tab in the Teams client. After a second or two, clicking on the Files tab showed the empty folder successfully. It didn't matter how long we waited to click on the Files tab, that message would be displayed and then go away the next time we clicked on the Files tab. This caused other issues for us as we were trying to add a custom SPFx tab as part of the team provisioning, and it would always fail when we tried to set it up as the channel in SharePoint could not be found. If we clicked the Files tab to get the General folder created and then tried to set up the SPFx tab, it would succeed. With additional research, we found that when using Application Permissions to add the team, the General folder never gets added to the Shared Documents library in SharePoint until someone clicks on the Files tab. However, if we used Delegated permissions to add the team to the group, the General folder is automatically provisioned after a second or so. If anyone else runs into this issue, you will need to use Application permissions to create the group and then use Delegated permissions to add the team. Cheers!
