Cannot Add external users to Sharepoint site despite being Group Owner

Question

I have created a Sharepoint Site (and hence I am the owner of that site).

Once on the newly created Site I do the following.

1. Click on the "Members" link on the top right of the page (Show a symbol and 3 Members).
2. Click on "Add Members"
3. Click on the "go to Outlook" link which opens the Outlook page of the Sharepoint Site
4. Click on the "Invite Others" link
5. Click on the "Email" button
6. Enter the email address of the external user and click send

The external user then receive an email stating "You're invited to join the "NameOfGroupHere" group.

When the external user clicks on this link the error below is displayed.

Can you please advise, as as it stands this product is completely useless as a product for collaborating with external clients.

Answer 1

Dear ProsolUK,

Good day!  Thanks for posting in Microsoft Community. 

From your description, it seems that you are trying to add external user to SharePoint site, however, getting error when trying to add guest user from Outlook page.

If my understanding is right, generally, we can easily share the site to the external user by navigating to site > settings > site permissions > advanced permissions and grant permission as shown below:

Step 1: Navigate to site permission page

Step 2: Grant permissions

For your reference: External sharing overview - SharePoint in Microsoft 365 | Microsoft Learn

Additionally, based on our testing, we cannot reproduce your issue on our side, would you please check if the invitations are sent to the group owner for approval? If not, please try removing and/ or re-adding the user to check if the issue still persists. For your reference: Manage guest access in Microsoft 365 groups - Microsoft 365 admin | Microsoft Learn

Below are the steps I have tried to add member to the group for your reference:

And the added member can access the site by clicking "Go to SharePoint" as shown below:

If the scenario above is not consistent with yours, you can also post back and point that.

Your understanding and patience will be highly appreciated. I hope that you are keeping safe and well!

Sincerely,

Rhoda| Microsoft Community Moderator