Unable to Open Excel File (invalid extension or format)?

Excel files are most likely the most “delicate” file types and most often present problems with opening. If you are in this article it means that you are also experiencing the error message “XXX file cannot be opened because the file format or extension is invalid” while opening the worksheet. Below is the image of the error you may see.

This article includes a list of possible solutions for this annoying problem. Read on to discover both the causes and the solutions!

As we all know, Microsoft Excel it is the most used application for personal and professional work. You can create standard financial reports, school reports and much more using this program. However, no single application is free from errors and the same case occurs in Excel program. If you are looking for a quick and reliable solution to resolve the “Cannot open Excel file because the file format is invalid“, we recommend that you download an Excel Repair software that is capable of repair damaged excel files. You can also recover data from Excel workbook with multiple worksheets.

Causes of the Problem

Typically, this error message occurs on those Excel workbooks that have been sent to a person for review purposes. In this situation, the Excel can’t open error can occur because:

  1. spreadsheet appears to be damaged or corrupt.
  2. The other reason is that the workbook (.xlsx) has a compatibility issue with the Microsoft Excel version.

To solve this problem, here we will provide the 3 best solutions alternatives to fix the problem in MS Excel.

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How to Fix “Excel File Cannot Open” Error

In the following sections we will see the solutions that can solve this technical problem in the appropriate way. Each technique is used for different purposes. So, choose according to your situation and needs.

Solution 1: Change the file format of your workbook

As stated before, the error message “Excel cannot open the file “filename.xlsx” because the file format is invalid” may also be displayed if you have any problems compatibility. For example, the spreadsheet has a different file extension that is not supported by Excel 2007. Therefore, it is recommended to check the file format first when you encounter this error. And, if you think the format is not appropriate for your Excel application, change it using the instructions below.

1. Launch the application MS Excel 2013 on the system.
2. Click the tab File to display the relevant menu.
3. Next, select the option Export from the drop-down menu.
4. Next, select Change file type in the section Export. Next, choose the option Workbook (*.xlsx) under the heading Change file type.

After performing the above steps, open the file in your Excel application again. Check that it now opens without the error message.

Solution 2: Use ‘Open and Repair’ feature

If the above solution fails to fix the error “unable to open excel file” then it is likely that the .xlsx file is damaged. To repair corrupted worksheet, Microsoft Excel already has a built-in function known as “Open and restore“. Its main function is to fix some minor corruptions in the spreadsheet and then open it in Excel.

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Note: All these steps are performed in the Microsoft Excel 2013 application.

1. Launch the Excel application and click on the tab File.
2. Go to the option You open and click Browse to load the damaged file.
3. From the window You openselect the file and go to the drop-down button You open.
4. Press the button and select Open and restore.

5. This way you will be able to repair the damaged .xlsx file.

Solution 3: Use Excel Repair Software

There are high chances that manual methods fail to fix this error message such as the error Excel cannot open the file “file.xlsx” because the file format or extension is invalid. In this case you need to enlist the help of a Excel repair software. For example, you could try the Toolkit Repair program, a tool developed to restore the contents of damaged .xlsx files and import them into a healthy one. This program does not alter the data and formatting of the file during the entire procedure. Furthermore, the software only takes a few minutes to repair the spreadsheet (.xlsx file). Simply follow the guidelines below.

Step 1. Download and install Toolkit Repair on your Windows PC

Here’s what you’ll see after installing and opening the program:


Step 2. Repair Excel files

Click on the “ iconRepair Excel File” and from the window that opens you will have to select the XLS or XLSX file to repair

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After importing the file click on SCAN and wait for the scan and subsequent repair.


Once the repair process is complete you will be able to preview the data of the excel file and proceed to save it into a working excel file.


In this post we have discussed about the methods and resolutions for the problem “Excel file cannot be opened because the file format or extension is invalid”. If you are also experiencing this type of message, use the techniques above to resolve the issue.

Here are other frequently asked questions related to the topic:

1. Can I repair a damaged Microsoft Excel spreadsheet?

Yes, you can restore a corrupt MS Excel spreadsheet using the Toolkit Repair recovery software seen above. This tool can recover the following items in the blink of an eye:
1. Repair rows and columns
2. Illustrations and other graphic elements
3. Cell comments
4. Applied formulas or functions
5. Pivot Chart, Pie Chart, etc.

2. What are the Excel related errors that this tool can fix?

This utility is quite popular to fix multiple Excel problems. Some of them are mentioned below:
1. The file is damaged and cannot be opened
2. The selected file is invalid
3. Excel is unable to open the file

3. How long does this software take to recover a damaged Excel sheet?

It depends entirely on the file size and configuration of your machine.

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