HOW TO FIX THE ERROR ATTACHED?

Start Excel in Safe Mode and test Save As on a new blank workbook; if saving works there, disable the add-ins that Safe Mode bypasses.

1. Test Excel in Safe Mode

Since Online Repair has already been completed and the problem affects every workbook, do not repeat workbook repair or Online Repair.

1. Close Excel.
2. Press Windows key + R.
3. Enter:

      excel /safe
   

4. Select OK. The title bar should display Microsoft Excel (Safe Mode).
5. Create a blank workbook, enter some data, and test File → Save As to a local folder such as Documents.

Safe Mode bypasses Excel and COM add-ins, startup folders, customized toolbars, and some changed settings, making this the supported next isolation test. ^1^

2. If Save As works in Safe Mode

Disable the COM add-ins:

1. While Excel is in Safe Mode, select File → Options → Add-ins.
2. At the bottom, set Manage to COM Add-ins, then select Go.
3. Record which add-ins are enabled, then clear every checkbox.
4. Close Excel and reopen it normally.
5. Test Save As again.
6. If saving now works, enable the add-ins individually, restarting and testing Excel after each one. Leave the add-in that causes the failure disabled and obtain an update from its publisher.

Microsoft’s troubleshooting procedure recommends this one-at-a-time test to identify the conflicting add-in. ^1^

If the problem remains with all COM add-ins disabled, repeat the test for Excel Add-ins from the same File → Options → Add-ins page. Avoid manually editing the registry unless necessary; incorrect registry changes can cause serious problems.

3. If Safe Mode also fails

Install available Microsoft 365 updates using another Office application if Excel closes too quickly:

1. Open Word and create a blank document.
2. Select File → Account.
3. Under Product Information, select Update Options → Update Now.
4. Allow installation to finish, restart Windows, and test Excel again.

If Update Options is unavailable, updates might be controlled by a volume license or organizational policy; use Windows/Microsoft Update or contact the organization’s IT administrator. ^2^

4. If updating does not resolve it

Perform a complete uninstall and reinstall, rather than another Online Repair:

1. Ensure the Microsoft account used for Microsoft 365 is available for reinstallation.
2. Use Microsoft’s uninstall troubleshooter on the affected PC.
3. Follow its prompts and restart when requested.
4. Reinstall Microsoft 365 and sign in with the licensed account.
5. Before adding third-party Excel add-ins, create a blank workbook and test Save As.

Uninstalling Office removes the applications but does not remove documents or workbooks. The troubleshooter supports Microsoft 365, Office 2021, Office 2019, and Office 2016 on Windows 10 or later; it currently does not uninstall Office 2024. ^3^

Because the same failure occurs in a new blank workbook, Open and Repair for individual files is not applicable; that feature is intended for corrupted workbooks rather than an Excel-wide failure.

References

1. Excel not responding, hangs, freezes or stops working | Microsoft Support
2. How to update Microsoft 365 or Office for Windows | Microsoft Support
3. Error 30088-26 when updating Office | Microsoft Support