Unable to sign in when accessing a shared SharePoint folder

Dear Morgan Julia,

Thank you for providing the detailed information and for already performing several troubleshooting steps. I understand how disruptive this is, especially since you're unable to upload documents to the shared SharePoint folder.

Based on your description, the issue appears to be isolated to the authentication process when accessing the shared SharePoint content, as your business OneDrive account is functioning normally.

To help narrow down the cause, could you please provide the following information:

1. Does the issue occur when accessing the shared folder from both SharePoint Online (web browser) and Microsoft Teams (if the folder is associated with a Team)?
2. Are other users able to access and upload files to the same shared SharePoint folder?
3. Are you an internal user of the organization that owns the site, or were you invited as a guest/external user?
4. If possible, please provide a screenshot of your issue and share it with me.

In the meantime, if you have access to another work account or browser profile, please try opening the shared folder in an InPrivate/Incognito window and ensure you are signing in with the same account that was granted access to the SharePoint folder.

Additionally, please check with the administrator of the shared SharePoint site whether your account was previously granted access to this folder and later removed and re-invited. Microsoft has documented a scenario where an external user can encounter the error: We're sorry, sign-in isn't working right now. But we're on it! Please try again later after the user's account is removed from the SharePoint site and then invited again using the same email address. In this situation, the original invitation may have created an account association that can cause authentication issues when a new invitation is sent.

If applicable, please ask the SharePoint administrator to review the affected user's permissions and previous guest account history on the site.

I hope these steps are helpful. Please try them and let me know how it goes. If the issue continues, please reach out again and let me know and we can work together to get this resolved.

Thank you for your patience and understanding and I look forward to continuing the conversation.

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