9 Methods for “The Last Time You Opened It Caused a Serious Error” in Excel!

The “Microsoft Excel: The last time you opened it caused a serious error. Do you still want to open it?” error message usually appears when opening the MS Excel documents. When this warning occurs, it means that Excel encountered a problem the last time it was opened, which caused it to crash or behave unexpectedly.

Here is the screenshot of the error:

Let’s check out this blog & understand the possible reasons behind this error, along with the fixes to resolve it.

What Causes the Last Time You Opened It Caused a Serious Error in Excel?

This frustrating bug can be caused by various unexpected reasons and lead to significant inconvenience. Here are the most common causes:

1. Corruption in the Excel file
2. Outdated Excel software versions
3. Due to corrupted or faulty add-ins
4. Malware or virus infections
5. Program to quit unexpectedly
6. Corrupted Office Suite
7. Insufficient system resources.

Is It Essential to Fix Excel Serious Error Immediately?

Yes, it is essential to fix Excel’s serious error immediately because it may restrict you from opening or accessing your crucial workbook data and can lead to severe data loss. So, consider solving this warning message promptly to access your spreadsheet data and ensure a smooth workflow.

Methods to Fix Microsoft Excel the Last Time You Opened It Caused a Serious Error

Try the following effective solutions to deal with this hectic situation.

Method 1- Reboot your PC

Restarting your computer can indeed be a useful solution for various problems including MS Excel serious error. When you restart your computer, it clears the system’s memory & may solve the temporary malfunctions that could be triggering this error.

Also Read: Fix “The File Is Corrupted And Cannot Be Opened Excel” Error

Method 2- Disable Faulty Add-Ins

In several community websites, many users have reported that they received the last time you opened it caused a serious error due to faulty Excel add-ins and hence, fixed by disabling them. So, you should also try to diagnose and disable the faulty add-ins in Excel to overcome this situation.

Follow the steps to turn OFF the Excel add-ins:

• Open the Excel application, and click on Options >> Add-ins.

• Under the Excel options window, choose the COM Add-ins from the drop-down >> click on Go button.
• Now, deselect all the checkboxes >> click OK.

• Restart your PC to check for the problem.

Method 3- Repair Corrupt or Damaged Excel Workbook

In Excel, many issues and errors appear due to Excel file corruption. Thus, if you are facing this error message due to corruption in the specific workbook, you can use a free Open and Repair tool.

Here is how you can run this feature:

• Launch the Excel application >> click on Open.
• Go to the folder to select the corrupt workbook.
• In an Open dialog box, choose the faulty XLS/XLSX file.
• Next, click an arrow next to Open button >> tap on Open and Repair.

• At last, click on “Repair” to recover as much of the workbook data.

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Steps to Use MS Excel Repair Tool:

Method 4- Fix The Last Time You Opened It Caused a Serious Error by Updating Excel

If you are using an outdated version of Excel software, it could be the reason for Excel crashing or not opening problems along with serious errors. To overcome this circumstance, try updating your Excel software to the latest version.

Here are the complete steps to update Excel software:

• Open Excel >> navigate to the “Account” option.
• Then, click on the “Update Options.”
• Now, click on the “Update Now” option to install the latest updates.

Method 5- Open Excel in a Safe Mode

The next method you can try to deal with Microsoft Excel the last time you opened it caused a serious error is opening the Excel file in a safe mode. However, this will help to easily detect any problematic add-ins that are generating this error & later disable them.

To know the steps to open Excel in safe mode, Click here.

Method 6- Check the Memory Usage

You can even check & close the unnecessary applications running in the system’s background to free up some memory. For this, follow the steps below:

To do so, follow these steps:

• Press the CTRL + ALT + DEL keys together on the keyboard >> click Task Manager.
• Next, go to the Processes tab & look for any unnecessary processes.
• Simply right-click on a process no longer needed>> choose End Task.

• Relaunch Excel to see if the error is fixed.

Method 7- Copy Excel Workbook Data to a New Workbook

Numerous users have confirmed that they are able to fix the last time you opened it caused a serious error Excel by copying data from the affected XLSX file to a new workbook.

Here are the steps to be followed:

• Find the location where the affected document is saved.
• Then, right-click on it to choose Properties.

• Under Properties window, click on ‘Read Only’ option in the General.
• After this, try to open the file in ‘Read Only’ mode.
• Now, if it opens, then copy all its data and paste it into a new file.
• Finally, save the file with another name.

Method 8- Repair MS Office Application

As already mentioned in the causes section, corruption in the MS Office suite can even lead to this peculiar error. To solve this, consider repairing the Microsoft Office application by following the instructions below:

• Go to the Start menu.
• Type Apps and Features or Installed apps in a search bar, then choose the result.
• Locate and select the MS Office entire package >> select Modify.
• In the How would you like to repair your Office Programs window, click on Quick Repair.

• Now, click the Repair button and follow the onscreen instructions until the process ends.

Also Read: Fixed- The Workbook Cannot Be Opened or Repaired by Microsoft Excel Error (8 Ways)

Method 9- Contact Microsoft Support Team

If none of the above DIY techniques work for you, then it is worth contacting the Microsoft Support team. They will surely assist you with troubleshooting steps and recommendations to get rid of this issue.

Related FAQs:

What Is Serious Error Opening Excel?

Serious error opening Excel occurs because the file seems on the list of disabled files for the MS Office program.

How Do I Get Rid of The Error Warning in Excel?

If you are not well aware of the exact reason behind the error warning in Microsoft Excel, you can follow these steps:

• Open the faulty Excel document >> click File tab >> Options >> Formulas.
• In the Error Checking, clear an Enable background error checking checkbox.

How Do I Fix an Excel File That Is Opening Error?

To fix an Excel file that is opening error, you can run the Excel’s built-in Open and Repair tool. Here’s how you can run this utility:

• Navigate to File > Open.
• Then, browse and choose the folder that contains the corrupted file.
• After selecting the corrupted workbook, click on Open >> Open and Repair >> Repair.

Final Thoughts

Above, I have discussed some tested ways to fix the last time you opened it caused a serious error Excel 365. But if the error has occurred due to Excel file corruption, try repairing it using the most reliable Excel Repair Software. It can fix multiple files without distressing the original formatting.

I hope you enjoyed reading this post!