What is the QuickBooks Error 121? Methods to Fix It

Last Updated on January 27, 2026

The QuickBooks error 121 is an update error that usually occurs when you are trying to update the QB Desktop application or payroll. It is generally caused by a lack of administrator rights while updating the software or program problems with the QB Desktop app. This can lead to a hampered workflow and have a negative impact on your business processes. You can resolve it by downloading the QB Desktop updates with admin rights and using the Quick Fix My Program tool from the QB Tool Hub. In this blog, we’ll cover the methods you need to troubleshoot the error code 121 in QuickBooks Desktop. First, let’s start with the causes of the 121 error.

Are you struggling to update your QuickBooks Desktop app and Payroll? Feel free to contact our Accounting Helpline’s experts at 1.855.738.2784 today to resolve your issue in no time!

Potential Causes of the QuickBooks Desktop Error Code 121

Given below are the potential factors that can cause the QB Desktop error 121 to appear on your screen:

1. A damaged QB company file.
2. A disabled QB File Copy Service.
3. An invalid or expired payroll subscription.
4. The Firewall is blocking your QB Desktop application.
5. An unverifiable digital signature certificate.
6. A missing file or component is needed for the payroll to update.
7. Program problems with the QBDT software.
8. A lack of administrator rights while updating the QB Desktop app.

These are the causes of the QuickBooks error 121.

Methods Resolve the QuickBooks Desktop Update Error 121

Listed below are the methods you can use to troubleshoot the issue of the QuickBooks error code 121:

Download the QB Updates With Admin Rights

The QuickBooks error code 121 can be caused by a lack of admin rights while updating the QB Desktop app. Follow the steps given below to fix it:

1. Close all your company files.
2. Exit the QuickBooks Desktop application.
3. Find the QB Desktop icon on your home screen.
4. Right-click on it.
5. Click on Run as Administrator.
   

Now, update to see if the error has been resolved.

Install a QuickBooks Digital Signature Certificate

You can install a digital signature certificate for QB Desktop to resolve the QuickBooks error 121 with the steps given below:

1. Navigate to the folder containing your QB program files:
   • Usually found in this location: C:\Program Files (x86)\Intuit\QuickBooks 20XX (XX represents the version of QBDT)
2. Locate the QB application file (.exe).
3. Right-click on it.
4. Select Properties.
5. Then, navigate to the Digital Signatures tab.
6. Select one of the entries in the Signature list field.
7. Press the Details option.
8. The Digital Signature Details window would open.
9. Press View Certificate.
10. The Certificate window would open.
11. Go to the General tab in the Certificate window.
12. Click on Install Certificate.
13. The Certificate Import Wizard welcome screen would appear.
14. Make sure the Store Location is on the Current User.
15. Hit Next.
16. Press Next again.
17. Hit Finish.
18. You would get a message stating that the import was successful.
19. Select OK.

Then, just repeat the steps for each Security Certificate on the Digital Signature list.

Use Quick Fix My Program

You can use the Quick Fix My Program tool from the QB Tool Hub to resolve the QuickBooks Desktop error 121 with the steps given below:

1. Download and install the QuickBooks Tool Hub.
   
2. Open the QB Tool Hub app.
3. Navigate to the Program Problems tab.
4. Click on Quick Fix My Program.
   
5. Let the tool run.

Now, the issue should be resolved.

Make Firewall Exceptions for the QB Desktop App

If your Firewall is blocking QuickBooks, make firewall exceptions for the QB Desktop app to patch QuickBooks error 121 with the steps given below:

1. Open the Start menu.
2. Search for and open the Windows Firewall.
3. Click on Advanced Settings.
   
4. Right-click on Inbound Rules:
   • You will create Outbound Rules later on.
5. Select New Rule.
   
6. Click on Port.
7. Hit Next.
8. Then, ensure that TCP is selected.
9. Go to the Specific Local Ports field.
   
10. Feed in the specific port for your QB Desktop version:
    • QuickBooks Desktop 2020 and later: 8019, XXXXX
    • QuickBooks Desktop 2019: 8019, XXXXX
    • QuickBooks Desktop 2018: 8019, 56728, 55378-55382
    • QuickBooks Desktop 2017: 8019, 56727, 55373-55377
11. Press Next after entering the port number.
12. Click on Allow the Connection.
13. Hit Next.
14. Ensure all profiles are marked if you are prompted.
15. Press Next
16. Create a rule
17. Name it something like QBPorts(year)
18. Hit Finish when you’re done.
19. Follow the steps again to create Outbound Rules, just right-click on Outbound Rules after clicking in Advanced Settings.

The error should now be patched.

Utilize the QB Install Diagnostic Tool

The QuickBooks Install Diagnostic Tool can be used from the QB Tool Hub to mend the QB error code 121 with these steps:

1. Open the QB Tool Hub app.
2. Navigate to the Installation Issues tab.
3. Click on the QuickBooks Install Diagnostic Tool.
   
4. Let the tool run.
5. It can take up to 20 minutes to finish working.

Now, you would be able to update your QB Desktop app.

Use the QB File Doctor Tool

The QuickBooks File Doctor Tool can be used to repair a damaged company file, which can be causing error 121 in QuickBooks, with the steps given below:

1. Open the QB Tool Hub app.
2. Navigate to the Company File Issues tab.
3. Click on Run QuickBooks File Doctor.
   
4. It can take up to a minute to open:
   • If it doesn’t open, search for QuickBooks Desktop File Doc and open it manually.
5. Choose your company file from the dropdown menu:
   • If you can’t see your file, click on Browse and search to find your file.
6. Select the Check your file option.
7. Press Continue.
8. Enter your QB admin password.
9. Click on Next.

The QuickBooks error 121 should be fixed now.

Update the QB Desktop App Manually

You can manually update the QB Desktop application if you’re facing the QuickBooks error code 121 with the steps given below:

1. Open the QB Desktop application.
2. Close all your company files.
3. Click on the Help menu.
4. Select the Update QuickBooks Desktop option.
   
5. Navigate to the Options tab.
6. Select the Mark All option.
7. Press Save.
8. Click on Update Now.
9. Mark the Reset Update checkbox.
10. Press the Get Updates option.
    
11. Close the QuickBooks Application.
12. Open it again to install the updates.

This would update your QB Desktop app to the latest version.

Verify and Rebuild Your QB Company File

If your QB Company file is damaged and you are facing the QuickBooks error code 121, you can use the verify and rebuild data utility to fix it with the steps given below:

1. Open the QB Desktop app.
2. Go to the File menu.
3. Click on Utilities.
4. Select Verify Data.
   
5. Then, navigate to the File menu again.
6. Select Utilities.
7. Click on the Rebuild Data option.
   
8. QB will ask to create a backup before rebuilding your company file.
9. Click on OK.
10. A backup is required to rebuild your company file.
11. Choose where the backup file would be saved.
12. Hit OK.
13. Ensure not to replace an existing backup file.
14. Enter a unique name in the File name field.
15. Press Save.
16. You will get the message stating that Rebuild has completed.
17. Click on OK.

Now, the QB Desktop error code 121 should be patched.

Check the Date and Time Settings on Your PC

If the date and time settings on your PC are incorrect, you can face the QuickBooks update error 121. If you want to patch the QuickBooks error 121, follow the steps given below:

1. Go to the home screen on your PC.
2. Right-click on the system clock in the bottom right corner.
3. Select Adjust Date/Time.
4. Then, select Change date and time.
   
5. Specify the current date and time.
6. Click on OK twice.
7. Close and reopen QB Desktop.

Now, try to update the QB Desktop app to the latest version to see if the error has been resolved.

Clean Install the QB Desktop App

As a last resort, you can clean install the QB Desktop app by manually renaming the installation folders to fix the QBDT error 121 with the steps given below:

Uninstall QB Desktop

1. Open the Start menu.
2. Search for and open the Control Panel.
3. Click on Uninstall a Program.
   
4. Choose QuickBooks Desktop from the list of programs you see.
5. Select Uninstall/Change.
6. Press Remove.
7. Click on Next.

Rename the QB Installation Folders

1. Open the File Explorer on your PC.
2. Go to the folder containing your QB Company file.
3. It’s usually in one of these locations:
   • C:\ProgramData\Intuit\QuickBooks (year)
   • C:\Users\(current user)\AppData\Local\Intuit\QuickBooks (year)
   • C:\Program Files\Intuit\QuickBooks (year)
   • 64-bit version C:\Program Files (x86)\Intuit\QuickBooks (year)
4. Right-click on the folder.
5. Press Rename.
6. Add the word old at the end of the folder name.

Install QBDT Again

1. Open the QuickBooks.exe file.
2. Choose between these two options:
   • Express Install
   • Custom and Network Options
3. Click on Next.
4. Hit Install.

This should fix the QuickBooks Desktop update error code 121.

QuickBooks Error 121 – A Quick View Table

In the table below is given a concise summary of this blog on the topic of the QuickBooks Desktop error code 121:

Conclusion

The QuickBooks error 121 is an update error that usually occurs when you are trying to update the QB Desktop application or payroll. It is generally caused by a lack of administrator rights during software updates or by program issues with the QB Desktop app. This can lead to a hampered workflow and negatively impact your business processes. You can resolve it by downloading the QB Desktop updates with admin rights. We have covered the potential factors that can trigger the 121 error to appear on your screen, along with the methods you need to troubleshoot it in this blog.

If you are still facing the QuickBooks update error 121, feel free to contact our Accounting Helpline’s experts at 1.855.738.2784 today to resolve your issue at a moment’s notice!

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Edward Martin

Edward Martin is a Technical Content Writer for our leading Accounting firm. He has over 10 years of experience in QuickBooks and Xero. He has also worked with Sage, FreshBooks, and many other software platforms. Edward’s passion for clarity, accuracy, and innovation is evident in his writing. He is well versed in how to simplify complex technical concepts and turn them into easy-to-understand content for our readers.