Be it collecting and representing data or verifying the business numerals, Excel is an amazing tool that helps businesses and individuals ease their data analyzing processes. But life gets tough when excel starts to malfunction. Various users have experienced a common excel error, i.e., “Excel cannot open the file because the extension is not valid.”
The error prevents you from opening your important files, thus, denying you any access to them. Are you someone suffering from the same error? Is your Excel file displaying the error “Excel cannot open the file because the extension is not valid” each time you try opening it? Well, we have got six verified solutions that shall help you ease the trouble and get rid of the error.

Fix 1: Fix Excel Cannot Open the File by Changing Excel File Extension
“Excel cannot open the file because the extension is not valid” error becomes annoying at times of need as it might prevent you from accessing your file. We shall start by attempting to fix the problem by changing the file extension. By default, Excel 2004-10 would save a file in XLS format while the later versions would save it in XLSX format. As the error highlights an error in the file extension, we shall proceed to changing the file extension to another type.
Step 1: Launch Microsoft Excel on your PC.
Step 2: Head to the “files” section, and click “Export.”
Step 3: In the section, select “change file type” and click on the file with the error.
Step 4: Change the file extension and save the file.

Fix 2: Fix Excel Cannot Open the File by Restoring the Previous Excel
If the above method didn’t sort out your problem, we might consider that the file isn’t fit for your excel version; hence we would restore it to an older version. The reason behind the error might be the infection of your PC due to a virus or malware, which leads to the malfunctioning of your computer. The following are the steps to restore your PC to an older version.
1. Locate the infected file in your file’s explorer.
2. Right-click to file and choose Properties from the menu.
3. Head to “previous versions” bar.
4. A list of previous versions shall be displayed, select one of them, and click “OK.”

Fix 3: Fix Excel Cannot Open the File by Using Open and Repair Feature
If both of the above methods have failed, we would need to use Microsoft office’s built-in repair feature. The feature helps fix any malfunctioning of the files and prepares them for smooth and trouble-free use. Follow the steps below to fix “Excel cannot open the file because the file format or file extension is not valid” error easily.
Step 1: Launch Excel at your computer and head to the files section.
Step 2: Click on “open” and select browse from the side menu.
Step 3: Select the file you wish to use and expand the “open” drop-down menu.
Step 4: Choose “open and repair option”.

Fix 4: Fix Excel Cannot Open the File by Recovering Unsaved Workbook
Sometimes "Excel cannot open the file because the extension is not valid" error is caused by power cut or improper save. The unsaved Excel can not open since it's corrupt due to such reasons. Microsoft Excel offers a great feature called "Recover Unsaved Workbook." By taking the assistance of this feature, the excel file can be recovered and then it can be opened. Here are the steps to recover unsaved workbook:
1. Launch MS Excel on your system and then click on the "File" tab.
2. Now, go to the "Info" section.
3. Click on the "Manage Workbook" option.
4. Choose the "Recover Unsaved Workbook" option.
5. Upon clicking the Recover Unsaved Workbook, Microsoft Excel will look for unsaved files then it will display them.
6. From the displayed file, open the file and save it again.

Fix 5: Fix Excel Cannot Open the File by Opening Safe Mode
If the Excel file still fails to open or the extension is not valid, then you should try to run Excel in safe mode and turn off the Add-ins option. In this way, you can also check for errors in MS Excel. Let's move to the procedure to resolve the problem.
Step 1: Press the "Window + R" key to launch “Command Prompt”.
Step 2: When the Command dialog launches, type excel/safe in the search field and hit the "Enter" button.

Step 3: When the Microsoft Excel launches in safe mode, click on the "File" tab and then click on "Options".
Step 4: Now, go to "Add-ins” section.
Step 5: Now, select the "COM Add-ins" option from the drop-down menu, and then click the "Go" button.

Step 6: Now, clear one of the add-ins from the displayed list and click on the "OK" button.

Fix 6: Fix Excel Cannot Open the File by Recovering Excel File
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Sum up
One of the worst misfortunes that could happen is, Excel cannot open the file because the extension is not valid. However, after going through this guide, you don't need to be worried about such situations as Tenorshare 4DDiG is there to rescue you in such troubles. With Tenorshare 4DDiG, you can recover your data within a few clicks. Also, if you have any doubt, feel free to ask us. Thanks for reading this. Don't forget to share it with your friends who need this solution.