Office Compatibility Issues

Fix Spreadsheet Compare Cannot Open Unprotected Excel Workbooks

Maira Mehtab Sep 30, 2026 870 views

Question details

Users are unable to open large Excel files in Spreadsheet Compare because the tool falsely flags them as protected.

How to Fix Spreadsheet Compare Cannot Open Unprotected Excel Workbooks

Product: Microsoft Excel / Spreadsheet Compare
Device & OS: not provided
Scenario: Comparing large or complex Excel workbooks using the Microsoft Office Spreadsheet Compare tool.
Observed behavior: Spreadsheet Compare reports that the files might be protected and fails to open them. However, shrinking the file size by reducing rows and columns allows the tool to open them successfully, indicating a potential size or memory limitation rather than actual file protection.

Before you start

Verify that your Excel workbooks do not contain any hidden passwords for opening or modifying, and check the approximate file size and row/column counts before proceeding with troubleshooting.

Solution 1Recommended

Reduce Workbook Size and Complexity

Since Spreadsheet Compare struggles with massive datasets, reducing the file size and removing unnecessary data often resolves the false protection error.

Spreadsheet Compare in Office 2019 Professional Plus has known limitations when handling very large files. When it runs out of memory or hits a complexity threshold, it may incorrectly throw a 'protected workbook' error. Shrinking the dataset is the most effective immediate workaround.

Create copies of your workbooks

Before making any destructive changes, create duplicates of the two Excel files you want to compare.

Remove unused rows and columns

Open the copied workbooks in Excel. Highlight empty rows and columns outside your data range, right-click, and select 'Delete' to clear any hidden formatting that inflates file size.

Save as an optimized format

Go to File > Save As, and choose 'Excel Binary Workbook (*.xlsb)'. This format handles large amounts of data much more efficiently and reduces the file footprint.

Run Spreadsheet Compare

Launch Spreadsheet Compare and attempt to compare the newly optimized .xlsb files.

Optimization Tip: Removing complex macros or external data links in the copied versions can also help Spreadsheet Compare process the files without crashing.

Solution 2

Seek Support on the Microsoft Q&A Forum

If reducing the file size is not an option, you may need specialist support from Microsoft to identify specific compatibility limitations in your Office edition.

Free Microsoft Office alternative

Use WPS Office for Seamless Spreadsheet Management

If Microsoft Excel's Spreadsheet Compare tool is bottlenecking your workflow due to file-size limitations, consider switching to WPS Office. It provides a lightweight, robust platform for analyzing and managing large datasets without heavy resource restrictions.

1. Download and Install: Get WPS Office for free from the official website and follow the simple installation prompt.
2. Open WPS Spreadsheet: Launch WPS Spreadsheet and navigate to Menu > Open to locate your large Excel workbooks.
3. Review Data Effortlessly: Use WPS Office's built-in View and Data tabs to manage, filter, and review large datasets without artificial size crashes.

Fully compatible with Microsoft Excel formats (.xlsx, .xls, .csv).Lightweight architecture handles large rows and columns smoothly.Free to download with a familiar, user-friendly tabbed interface.Built-in advanced data review and management tools.

microsoft office alternative - wps office

Frequently Asked Questions

Why does Spreadsheet Compare say my unprotected Excel file is protected?

This is typically a false error triggered by memory limitations or file-size constraints. When Spreadsheet Compare struggles to process massive row/column counts or complex formatting in Office 2019, it mistakenly interprets the processing failure as file protection.

Is there a maximum file size for Spreadsheet Compare?

While Microsoft does not explicitly document a strict hard limit, users frequently report failures and false protection warnings when dealing with files exceeding several megabytes, hundreds of thousands of rows, or heavy formatting.

How can I verify if an Excel workbook is actually protected?

Open the workbook in Excel, go to the 'Review' tab on the ribbon, and check the 'Protect Sheet' or 'Protect Workbook' buttons. If the buttons say 'Unprotect Sheet', the file genuinely has protection applied.

Does saving as .xlsb help with Spreadsheet Compare issues?

Yes. The Excel Binary Workbook format (.xlsb) stores data more efficiently than standard .xlsx files. Converting your workbooks to .xlsb significantly reduces their file size, often allowing Spreadsheet Compare to process them without throwing false errors.

Office App Problems