How to resolve this error message when opening Excel files

Question

For some reason I get pop-ups when opening certain Excel files, I have to close them or hit Escape to minimise them and it raises the same error message each time, any ideas or workarounds? I have no connection to [Moderator note: personal info removed] and never have had any connection! Please help!

Below is the Error message ID I get (I have anonymised it a bit):

Request Id: [Moderator note: personal info removed]

Correlation Id: [Moderator note: personal info removed]

Timestamp: [Moderator note: personal info removed]

Message: AADSTS50020: User account '[Moderator note: personal info removed]@XXX.com' from identity provider [Moderator note: personal info removed]/' does not exist in tenant '[Moderator note: personal info removed]' and cannot access the application '[Moderator note: personal info removed]'(Microsoft Office) in that tenant. The account needs to be added as an external user in the tenant first. Sign out and sign in again with a different Azure Active Directory user account.

Answer 1

Hi @AW

Please understand that our forum is a public platform, and we will modify your question to cover your personal information including your organization domain name, ID in the description. Please notice to hide these personal or organization information next time you post error or some information to protect personal data.    

I have moved the information to the Private message if you need to add any more privacy information please add it in there.

Regarding your issue, the error indicates that the workbook is attempting to access a Microsoft 365 resource (such as a link, embedded connection, or sign‑in context) that belongs to another tenant. Because your account doesn’t exist in that tenant, Excel keeps prompting you to sign in and throws the AADSTS50020 message. This can happen even if you personally have no connection to that organization, as the reference may be embedded in the file itself or tied to a previous sign‑in context. 

For more details, please refer to: Error AADSTS50020 - User account from identity provider does not exist in tenant

Also, may I kindly ask a few questions to help understand it better: 

• Where are the affected files stored (for example: local drive, OneDrive, SharePoint, or email attachment)? 
• Were these files created by you, or were they shared or received from someone else? 
• If you open the same file in Excel on the web, do you see the same error? 
• When the pop‑up appears, are you signed into Excel with any work or school account (check under File > Account)? 
• When the file is open, do you see anything listed under Data > Queries & Connections > Workbook Links? If you see any links or connections pointing to an unfamiliar organization, try removing or breaking those links to see if it helps with your issue. For more details, please refer to: Manage workbook links

Hope to hear back from you soon.  

The initial response may not fully address your needs, but it will help me better understand your situation. Once I get the information, I will try my best to find the next steps. 

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Answer 2

The error message indicates that the Excel files are trying to access a SharePoint/OneDrive or other Microsoft 365 resource in the Azure AD tenant "Challenger Group Services Pty Limited," but the signed-in account does not exist in that tenant. This is an Azure AD sign-in/authorization issue, not a problem with the Excel application itself.

To work around or resolve this behavior, use one of these approaches:

1. Sign out of the wrong tenant context

• In any Office app (Excel, Word, etc.), go to File → Account.
• Under User Information, sign out of all accounts.
• Close all Office apps.
• Reopen Excel and sign in only with the account that should have access to the files (for example, the account from the correct organization/tenant, not anything related to "Challenger").
• Open the file again and check whether the pop-up still appears.

2. Remove or update external data/links in the workbook The workbook may contain:

• Links to SharePoint/OneDrive locations in the Challenger tenant.
• Embedded objects or queries that connect to resources in that tenant.

To reduce prompts:

• Open the workbook.
• If prompted, cancel or close the sign-in dialog.
• In Excel, go to Data → Edit Links (if available) and check for links pointing to unknown or old locations. Break or update those links.
• Check Data → Queries & Connections for any queries pointing to URLs or data sources belonging to the Challenger tenant and remove or update them.

3. If the file is stored in a tenant you no longer belong to If the file itself is stored in a SharePoint/OneDrive site in the Challenger tenant (for example, opened via a shared link in the past), and that tenant no longer recognizes the account:

• Save a local copy of the workbook (for example, via File → Save As to a local folder) and open that local copy.
• If the local copy still prompts, remove or update external links and connections as in step 2.

4. Use the correlation ID if IT/admin support is available If an organization manages the account:

• Provide the Correlation Id, Request Id, and Timestamp from the error to the Microsoft 365/Azure AD administrator.
• The admin can search the sign-in logs using the correlation ID to see exactly which resource or app is being requested and adjust access or configuration accordingly.

If none of the above helps and the prompt appears for every file (not just specific ones), fully repairing or reinstalling Office can be used as a general remediation step, as shown in similar Excel error scenarios:

• Close all Office apps.
• In Windows, go to Control Panel → Programs → Uninstall a program.
• Select Microsoft 365 (or Office) → Change → Online Repair → Repair.
• Restart the device and test again.

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References:

• "An error occurred when sending commands to the program" in Excel
• SharePoint Correlation ID in error messages: what it is and how to use it