what is "[Moderator note: Personally Identifiable Information removed]" ID mean for SharePoint online error

Hi Zou, 

Thank you for sharing the details of what happened. 

As this is a user-to-user community forum, I do not have the ability to directly access or modify your account or service. However, I can provide guidance, recommend next steps, share applicable resources, and direct you to the appropriate support channels so the issue can be investigated further. 

Based on the information provided, you are a subsite owner with Full Control, but you are unable to access the following SharePoint permissions page: /_layouts/15/user.aspx 

This behavior may be related to inconsistent permission assignment, owner group association, or effective permissions on the affected subsite. The Correlation ID below can be used for backend log investigation if the issue needs to be escalated to Microsoft Support.

To troubleshoot and resolve the issue, please have a Site Collection Administrator or SharePoint Administrator perform the following steps: 

1/ Access the subsite permissions page as an administrator 

• Open the affected subsite permission page directly:  https://<tenant>.sharepoint.com/sites/<site>/<subsite>/_layouts/15/user.aspx 
• If the Site Collection Administrator can access this page, the issue is likely related to the affected user’s permission assignment, owner group, or effective permissions on the subsite. 

2/ Check the affected user’s effective permissions 

• Go to Settings > Site permissions > Advanced permissions settings > Check Permissions 
• Enter the affected user’s account and verify whether the user actually has Full Control at the subsite level. 

3/ Remove and re-grant the user’s permission 

• If the permission result is incorrect or inconsistent, remove the affected user or owner group from the subsite permissions, then add them back with Full Control. 

4/ Validate the subsite owner group 

• If the subsite owner group was manually created or appears to be incorrectly associated, create a new SharePoint group for the subsite owners, add the affected user to that group, and grant the group Full Control on the subsite. 

5/ Test again using a private browser session 

• After the permission changes are completed, ask the affected user to test again using an InPrivate or Incognito browser window to avoid cached authentication or stale permission data. 

Additional guidance that may helpful: 

• Access Denied or You need permission errors in SharePoint Online and OneDrive - SharePoint | Microsoft Learn 
• Manage site admins - SharePoint in Microsoft 365 | Microsoft Learn 

If the Site Collection Administrator or SharePoint Administrator also cannot access the page, or if the issue continues after rebuilding the permissions, I recommend submitting a support ticket with Microsoft Support through the Microsoft 365 Admin Center. They have access to system-level diagnostics and can investigate the issue more thoroughly. At the very least, they can help provide the most effective workaround to ensure your experience remains smooth and secure. 

When reaching out to Microsoft Support, please include the following details: 

• Correlation ID 
• Exact affected URL 
• Affected user 
• Date and time of the error, including timezone 
• Confirmation of whether a Site Collection Administrator can reproduce the issue 
• Confirmation that the subsite has unique permissions 
• Recent changes to permissions, groups, migration, or the user account 

In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support    

For detailed guidance on how to open a support ticket with Microsoft Support, please refer to: Get support - Microsoft 365 admin | Microsoft Learn  

I hope this helps move the case forward. Should you have any further questions or need additional assistance, please feel free to share them in the comment below. I'm very happy to help.  

Thank you again for your patience and understanding.

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