6. Stop Sage 50 from running

1. Close Sage 50.
2. Use the Task Manager to force Sage 50 to close.
   •  NOTE: Task Manager will allow you to stop Sage 50 if it's stuck open in the background  

7. Repair your Sage 50 install

1. Go to Control Panel, and then Programs and Features.
2. Verify that Sage 50 shows up on the list.
   • If not, proceed to the next section
3. Double-click Sage 50 and select Repair on the next screen.
4. When the Repair finishes, reinstall the latest service release. 

8. Run the Microsoft Program Install and Uninstall troubleshooter

1. Follow Microsoft Support's steps to fix problems that block the installation or removal of programs.
2. Download the troubleshooter from Microsoft Support and run it.
3. When asked if you’re having a problem installing or uninstalling a program, select Installing.
4. On the list of programs, select the Sage 50 Accounting version you’re trying to install.
   • If you don't see it, select Name not available
5. Click Next.
6. When prompted, answer Yes, try uninstall.
7. When the troubleshooter finishes, reinstall Sage 50 Accounting.

9. Clean up the Windows Registry

1. Create a backup of the Windows registry.
2. Press the Windows key and letter R at the same time on your keyboard, then type in regedit, then click Ok.
3. In the registry editor, browse to HKEY_CLASSES_ROOT\Installer.
4. Go to Edit and select Find...
5. In the search field, type in Sage 50 and click Find Next.
6. Delete the Registry Key that contains the Sage 50 Accounting 20xx Product Name entry for the version you're installing. The key will be one of the following:
   • {0068FE61-EBAA-4F22-9D76-479DCBA14513}
   • {16EF8600AABE22F4D96774D9BC1A5431}
   • {1768BEA4-3469-45FB-8EFB-6742E1C0E86F}
   • {54E4EECE-61B9-4D85-9B3C-99686A9ED6A1}
   • {6A4CCB61-447D-432E-B56A-7D5D7626E7B5}
   • {6CD774DA-B798-4D1E-B327-2AA6EA407929}
   • {7F70C7CF589E9D14A8F407C90E534D64}
   • {A09D9DC3A-156B-4785-9C7B-43DAC2D662A6}
   • {B4FDAA4D-37BD-4DF4-8531-B4F7ABC74E62}
   • {D2ADA6F5-F155-4A37-87CA-599E81F6C6C0}
   • {F3A0C9f5-77DD-4DE2-A2DF-7DB0687BA092}
   • {FC7C07F7-E985-41D9-8A4F-709CE035D446}
   • {F0F9B5DD45973A546964F2E7ABD1764B}
7. In the registry editor, browse to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall.
   • If you have a 32-bit version of Windows instead browse to HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall
8. Go to Edit and select Find.
9. In the search field, type in Sage 50 and click Find Next.
10. Delete the Registry Key that contains the Sage 50 entry.
11. Close the registry.
12. Go to Start, Run.
13. Enter in C:\Windows\Installer\ and click OK.
14. Rename the folder referenced in the error message, for example {0068FE61-EBAA-4F22-9D76-479DCBA14513} to Old.
15. Start the installation again.

10. Clean up the Windows Registry for the Tax Forms

1. Create a backup of the Windows registry.
2. Press the Windows key and letter R at the same time on your keyboard, then type in regedit, then click Ok.
3. In the registry editor, browse to HKEY_CLASSES_ROOT\Installer.
4. Go to Edit and select Find...
5. In the search field, type in Sage 50 Accounting Tax Forms or 7A4FE1AB76BAB294C9D7A4EE345F3A6C and click Find Next.
6. Repeat steps 4-5 until the search returns with no entries found.
7. Delete the registry key for the Sage 50 Accounting Tax Forms entry.
8. Verify you can install the Signature Tax Forms.