Thank you so much for getting back to me, @Brainy Cai!
I hope you can understand that my initial reply was intended to gather more details about your situation, which means that sometimes it may not provide an immediate solution or fully resolve your issue right away. I truly appreciate your patience and collaboration as we work through this together. Please take a look at the information below, which should help guide the next steps.
Based on the error information you’ve shared, it appears the issue is related to AADSTS500571 – Guest user account is disabled. This error typically occurs when a guest user is flagged as risky in their home tenant and is not related to any new country-specific rules or restrictions.
In this case, simply asking the SharePoint owner to remove and re-add you to the group won’t resolve the problem. You’ll need to contact the Global Admin or IT department of your partner organization to review and address this scenario. They can check the account status and take the necessary steps to enable it.
You may share this reference with them and ask them to try enabling your account via the Microsoft Entra portal or through PowerShell: Fix Sign-in Error Code AADSTS500571
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If the issue persists even after enabling the account, you can ask the admin of that organization to remove your account and re-add it in the Microsoft Entra ID portal and then have the SharePoint owner add you back to the group and check again.
If this answer helps clarify your situation and provides useful guidance, please consider clicking “Accept Answer” and kindly upvoting it. If the issue still persists, please don’t hesitate to reach out again, I’ll be here and happy to assist further, so you can feel confident that support is available.
Thank you once again for your patience and collaboration!
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