External users can't open the app

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Posted on by meelamri

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Hello,

I have a Canvas Apps that uses SharePoint as a datasource. The app is shared with external users.
Once an external user open the app, they receive the following error: "An error occured during athentication":

After investigation, the original error was: Canvas PowerApp: Failed to get onbehalfof access token: connectionId=sharepointonline, message=MSGraph discovery endpoint.

The weird part is: Once the user opens the SP list via its URL, then the user is able to open the app without any problem.
My problem really looks like the following thread: https://powerusers.microsoft.com/t5/Building-Power-Apps/Canvas-PowerApp-Failed-to-get-onbehalfof-access-token/m-p/1708370

Also, when I move the app to another tenant. External users can open the app without any issue. So, I think that it's related to the tenant or SharePoint.

Thanks,
Mehdi

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WarrenBelz 156,454 Most Valuable Professional on at

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Hi @melamri ,

Two things here. SharePoint needs to be shared with the user before they can see data and they also need to be logged into this connection in another tab in the browser to then open the App link (in the browser),

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meelamri 468 on at

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Hi @WarrenBelz ,

Thank you for your feedback.
Yes, SharePoint is shared with external users. But, I don't understand this part: also need to be logged into this connection in another tab in the browser to then open the App link (in the browser). Is this special for external users? I don't think so. Because I don't have this behavior in another tenant with the same app.

Thanks,
Mehdi

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WarrenBelz 156,454 Most Valuable Professional on at

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Hi @melamri ,

I have shared a number of apps with external users across a number of different Tenants (both app source and shared target) and can in my experience (every time), unless they establish the SharePoint Data connection in the browser first (or have it logged in already with "stay logged in" set), they can open the app, but cannot see any data. I find your comment interesting that you have another example where this does not happen.

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meelamri 468 on at

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Hi @WarrenBelz

I think it's pretty weird too. I've shared quite a few applications with external users in different tenants and this is the first time I've faced this issue. I think it's related to the tenant or a configuration on SharePoint that blocks the first authentication from Power Apps. In fact, once the user navigates to the SharePoint list via its URL, the user can use the application without any problem.

Thanks,
Mehdi

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WarrenBelz 156,454 Most Valuable Professional on at

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Hi @melamri ,

It may be a security setting in the "target" tenant (although I am unaware of where), although mine seem to have all been the same as I posted. How long ago did you do the ones that "worked" - mine have all been in the last 12 months.

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meelamri 468 on at

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Hi @WarrenBelz ,

The problem is no longer relevant. Users can now open the app without any issue.

Thanks,
Mehdi

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