Excel File Due to Invalid Extension

Excel is an exceptional tool that assists businesses & individuals to perform data analyzing processes with ease.

However, it is quite common to encounter errors and issues while handling MS Excel. One such error that users are recently experiencing and reporting is- “Excel cannot open the file because the extension is not valid.” Here is what the error looks like:

extension is not valid

The above error message occurs when trying to open an older version of an Excel file in the newer version. However, it is important to solve this annoying error ASAP.

Therefore, here I have discussed a few effective methods using which you can fix unable to open an Excel file successfully.

Read further for more info…

What Causes Excel Cannot Open the File Because the Extension is Not Valid.?

There are numerous reasons behind the occurrence of this peculiar error message. Some of the major causes are:

  1. The Excel file is corrupted or incompatible with the recent Excel version.
  2. The Excel document was received via email.
  3. Due to editing the document several times in different Excel versions.
  4. Different or incorrect extension.

As you have known the causes that triggered this error, now let’s proceed to get rid of it with the best fixes.

Methods to Fix Unable to Open an Excel File Due to Invalid Extension

Please Note: Before trying the below workarounds, create an extra copy (backup) of your Excel file that you are unable to open & then try the below steps on that backup copy.

Method 1- Change the File Format

As already mentioned in the causes section, an incorrect or different extension may trigger cannot open the file error in Excel. However, to solve it, you can try to change the default file format.

Follow the below steps to do so:

Step 1- In Excel 2010 & later versions, you need to click on a File menu. But for Excel 2007 & earlier versions, simply click on an Office button.

Step 2- On the left panel, you have to click on Options.

Step 3- Under the ‘Excel Options’ window, in the section Save workbooks, then click the “Save files in this file format” dropdown.

Step 4- Choose a file format (for example, the format supported by the version of your Excel). Click OK.

version of your Excel

Now, try to open your XLSX document. If not, then try the next solution to repair Excel file.

Method 2- Use Open and Repair Utility

Another method that you can try to troubleshoot this error message is to use the “Open and Repair” utility. It is an in-built Excel tool that allows you to fix different errors in Microsoft Excel including the “cannot open the file due to invalid extension” error.

To use this feature, follow the steps:

  • Open the Excel.
  • Next, click File menu and then “Open”.
  • In an Open dialog box, you have to select the Excel file that is showing an error when trying to open.

trying to open

  • Next, click on the down arrow on an Open button >> click on the “Open and Repair”.

Open and Repair

  • Now, MS Office will start checking and repairing the problems in the file.
  • Click on Repair for retrieving maximum data.
  • In case, if the Repair option fails, then click on the Extract Data button to recover data without values & formulas.

values & formulas

Method 3- Try to Open the File in a Safe Mode

You can even try to open the inaccessible XLSX or XLS file in safe mode. Running the Windows PC in a Safe Mode allows users to solve many issues with the OS as it boots vital system programs & services.

Here is how you can use a safe mode to fix the error:

  • Firstly, press on Windows + Rkeys together to open a Run dialog box.
  • There, type “exe/safe” & hit OK button.


  • After that, find the document in Excel & save it as .xlsx.
  • Then, close the application & restart the PC, so you’re no longer in the safe mode.
  • Now, open the Excel file as usual.

Method 4- Recover the Unsaved Workbook

Many users have reported that they received unable to open an Excel file error when trying to open an unsaved Excel workbook. In that case, you can attempt to recover the unsaved workbook by following the below steps:

Step 1- In Excel, click on the File menu.

Step 2- From an Info screen, in the Manage Versions, simply click on the “Recover Unsaved Workbooks” option.

Recover Unsaved Workbooks

Now, Excel will list any unsaved files. Simply attempt to open the file & save it.

Method 5- Restore Previous Excel

It might be possible that the file is not fit for the Excel that you’re using. Hence, it is suggested to restore it to the older version to deal with this error.

Follow these steps for restoring your computer to the older version:

  • Go to File Explorer >> locate an infected file.
  • Right-click on that file >> choose the Properties >> “previous versions”.

previous versions

  • Now, a list of earlier versions should be displayed, choose one of them >> click “OK.”

Automatic Way- Use Recommended Excel File Repair Tool

If the above methods fail to fix Excel cannot open the file, you can use the versatile Excel repair software- Stellar Repair for Excel. It can help you to regain access to your Excel file & its data.

Moreover, this program has the ability to repair corrupted XLS and XLSX files along with recovering all the worksheet stuff like pivot tables, charts, formulas, cell comments, chart sheets, filters, images, etc.

Therefore, just download, install, and try this Excel repair tool to repair Excel files.

Here’re the comprehensive steps to know how this program works:

  • Launch the Stellar Repair for Excel

Excel tool

  • Next, browse & find the corrupt Excel file(s) you want to fix. Then, click Repair

Repair option

  • After that, the utility will show the progress of an Excel file repairing process.

repairing process

  • Now, the program will display the preview of your fixed XLS or XLSX Simply check & click on the “Save File” option on the File menu if everything is OK.

everything is OK

  • At this time, click Browse to choose the location where you want to save your fixed file. Click OK.

Click OK

  • The software will show the progress of a file-saving process.

saving process

  • Finally, your repaired Excel document gets saved successfully on the chosen location of your computer.

your computer

That’s all.

To Sum Up

In this blog, I have discussed the possible causes behind the unable to open an Excel file error. However, all you need to do is to follow the above-mentioned solutions to deal with this annoying error.

In case, if the Open and Repair utility and other manual methods fail to fix this error, consider using an advanced Excel repair tool– Stellar Repair for Excel. This program makes the process of repairing an Excel file smooth & quick.

Thanks for reading!