8 Fixes To Resolve Excel The File Format And Extension Don’t Match Error

Receiving Excel file format and extension don’t match. the file could be corrupted or unsafe error? In that case this blog is going to be super beneficial for you. As it covers all the necessary details regarding Excel file format and extension don’t match error and ways to troubleshoot this on your own.

Before approaching the fixes let’s know about the reasons behind this Excel File Format And Extension error.

What Are The Causes Of ‘File Format And Extension Of Don’t Match’ Error?

Knowledge about the reasons for this file format and extension don’t match when opening Excel errors is important to apply the right solution.

  •       Wrong Extension

This specific error mainly occurs because of the wrong or different extension. This scenario arise either when the file is converted to some other format or due to user’s manual intervention.

  •       Excel File Is Blocked

In the Downloaded file of email attachments chances are high that properties levels are set blocked. As most of the email senders keep the properties blocked just for the sake of security purposes. So this is also one of the reasons behind why Excel file could be corrupted or unsafe error.

  •       File’s Incompatibility With Excel

Another reason can be that the file which you are trying to access is not incompatible with your Excel application.

  •       Protected Views is Enabled

Presence of a security option in your PC may be preventing the Excel application from opening certain files received through mail.

How To Fix File Format And Extension Don’t Match Error In Excel?

 Below are some best applicable fixes to resolve Excel file and extensions that don’t match error.

Solution 1# Changing The Extension Manually

As through the error message you all must have noted that something went wrong in the Excel File Format and Extension. Maybe the Excel file which you are trying to open is in some different extension or unsupported format.

So to fix this you must try changing the extension of your Excel file to some other format.

Here is the quick guide on how to apply this step:

  • First, go to the File Explorer and hit the View tab.
  • Now from the opened menu bar, go to the show/hide group. Within this group there is an option File Name Extensions, put a check mark across that.


  • After enabling the file name extension, go to the location where you have saved your error showing Excel file.
  • Make a right click over that file and select the rename option.
  • Change the extension to any of these formats: .xls or .xlsx or .xlsm and after every modification try to open your file.

In this way you will get the correct format which can easily open your Excel file without showing any error message.

Solution 2# Disable Add-ins

1: Press CTRL key from your keyboard and along with that tap to the Excel application icon. Very soon a confirmation dialog box will pop-up that will ask you to start your application in Safe mode.

2: If even after starting the application in safe mode, the problem persists then close your Excel application. Now start your application normally and try disabling the add-ins one by one.

3: Follow these paths to disable the add-ins: File > Options tab.

disable add in in excel 1

4: In the opened window of Excel options, go to the left pane and hit the Add-ins tab.

5: Now hit the Go button present beside the Manage: Excel Add-ins.


6: After that from the appearing list of Add-ins, uncheck each of the add-ins one by one to disable it.

disable excel add-ins

It’s time to check whether the problem has been resolved or not.

Solution 3# Unblocking The File

Excel file format and Extension of don’t match error also originates because it is blocked at properties level. Usually this problem is associated with receiving through email attachments or downloaded files on the internet.

This problem can be easily fixed by optimizing the file’s properties to unblock it.

Follow the below given steps to unblock Excel file:

  • Make a right click over the error showing Excel file and choose the properties option.

Unblocking excel file

  • Now in the opened properties window move your cursor down here you will get the security section and then hit the “unblock” button.

Unblocking excel file 1

  • After this step your Excel is now unblocked. So try re-opening your Excel file and check whether this time the problem is resolved or not.

If still you are getting the same Excel file extension won’t match error then move on to our next solution.

Solution 4# Open And Repair Inbuilt Tool

Open and repair inbuilt tool is the best option to resolve minor corruption or issues occurring in Excel files.

  • Hit the file tab and choose the open option.

Open And Repair Method

  • Make a selection of the Excel file in which you are frequently getting this error.
  • Now hit the arrow sign present next to the open Now from the drop-down menu choose the open and repair option.

Open and Repair

  • After that hit the repair button.

excel open and repair

  • If in case, this repair solution won’t fix the issue then repeat the above steps and hit the “Extract Data” option.

excel open and repair 2

  • In this way you can very easily extract data from your Excel file.

Solution 5# Disable The Protected View

File extension don’t match error also occurs when some new security option like protected view prevents the opening of certain Excel files.

Mainly such type of issue arises with the Excel files which were received through the email attachments.

Well this security setting can be easily cracked by disabling the protected view feature. So, here are the steps that you should follow to disable the Protected View setting.

  • Open your Excel application.
  • Hit the File> options tab.
  • This will open the Excel options settings window.

Change the Protected View Settings

  • From the left side navigation pane, choose the Trust-center tab.
  • Now from the opened window hit the Trust Center Settings.
  • On the left side of the Trust Center window, you have chosen the Protected View.

Turn OFF The Protected View Option

  • After that unselect all the previously selected options present within the protected view.

Protected View option 

  • Hit the Ok button to close the window.

Solution 6# Suppress The Error Warning Message

Another alternative option that you can try to fix Excel file format and extension of don’t match error is by creating the registry key to suppress this warning error message.

Note: making changes in the system registry setting is a bit risky and it can put your PC in a cumbersome situation.

Here is the quick guide on how you can suppress this file format and extension of don’t match error in Excel through the usage of registry editor:

  •   Hit Windows + R key together this will open the dialog box of Run.
  •  In this Run box, enter the text ‘regedit’ and hit the Enter button. This will open the Registry Editor.


  • Now in the prompt box opened through UAC (User Account Control), you need to hit the yes button.
  • After getting into the Registry Editor utility, go to the right side pane and search for the following path.

regedit 1


Note: as an alternative option you can also copy paste this location on the navigation bar and hit the enter button.

In the above given path” x” is to be replaced with your currently installed MS Office version.

  • After getting into the correct location, shift to the right-side pane, and make a right-click over the empty space. Choose “NEW” and then “Dword (32-bit) value”.
  • Name this DWORD value as Extension Hardening. After that, double-tap over it.
  • Now set the Base as Hexadecimal and value as 0.
  • Once you complete all these changes, shut down the Registry Editor and give a restart to your PC.

After the fresh start of the system you won’t get this annoying Excel error message.

Solution 7# Fix Excel File Corruption

If you are still getting the file format and extensions don’t match when opening Excel error then it’s recommended to use MS Excel Repair Tool. This is the best tool to fix any sort of issues, corruption, errors in Excel workbooks.

So if you are getting this error because of Excel file damage or corruption issues then this tool will surely resolve it.

With the help of this tool, you can easily restore all corrupt Excel files including the charts, worksheet properties, cell comments, and other important data. This is a unique tool to repair multiple Excel files at one repair cycle and recovers the entire data in a preferred location.

Steps To Repair Corrupt Excel File:

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Solution 8# Open Excel File Without Excel

If your Excel file is refusing to open because of the file format or extension issue then you can try to open it using 3rd party apps. Yes, there are so many alternative options available to open Excel files without Excel.

Here are the following options using which you can easily perform this task: Chrome Browser’s Free Extension; Excel Viewer, Apache Open Office and many more.

Final Verdict:

Now you can fix Excel file format extension doesn’t match the error on your own. But make sure to follow the given fixes very carefully.

Moreover, feel free to run the Excel repair tool, to fix any type of internal issues and errors that might be causing the error in your Excel file.

If I missed out on any solution on how to fix Excel file format and extensions don’t match error. Or if you have any other trick to share, then do share it with us on our Facebook page.

Priyanka is a content marketing expert. She writes tech blogs and has expertise in MS Office, Excel, and other tech subjects. Her distinctive art of presenting tech information in the easy-to-understand language is very impressive. When not writing, she loves unplanned travels.