QuickBooks Error 1601 occurs when the installation is not updating and the error code messages occur while working on this application. However, there are few general things that the user might want to know about the application he is trying to use.

What are the causes of QuickBooks Error 1601?
There are several causes behind the above java error code 1601 in QuickBooks, namely,

This is caused when the windows get infected with an endemic attack to associate software package.
The issue is caused when QuickBooks downloading file is faulty.
This issue is also caused when the Microsoft Installer gets corrupted.
Windows installer error 1601 occurs when there is no permission to put in the QuickBooks system or a Windows Operating System.
This issue also occurs when all the files are bolted.
All programs area unit infected with a malware result in error 1601 as well.
How to fix QuickBooks Java Install Error 1601 to help install QuickBooks?
There are various solutions to this. Here are some of them that could fix “Error 1601: Windows Installer is not accessible” for once and all:

Solution 1:
Click on the Start button and in the search window, enter ‘msc’.
Choose SERVICES (LOCAL) and then click the right mouse button on ‘WINDOWS INSTALLER’ and PROPERTIES.
Now, in properties on the Startup-Type, check if the option is ‘DISABLED’. If it is so, then click and select the option as ‘MANUAL’.
There, the user can click on ‘SERVICE STATUS’ and then set it to ‘START’ to enable Windows.
If the error was caused by the Windows installer, then this will solve the issue for you. If not, we have a couple of more solutions to such issues.
You May Also Read: How to Fix Quickbooks Abort Error

Solution 2:
Go to the Start button in the Windows and then enter ‘cmd’ in the search option to display the Command Prompt option.
Then type, “msiexec/unregister”. Press Enter key and close the command prompt window.
Logout out of Windows and restart the computer. The user then has to install the program that caused the Windows Installer service error.
Solution 3:
Go to the Start button and press the Windows+R button.
Now, in the command prompt, type ‘exe/unreg’ and click on OK.
When there will be a pop-up dialog box message asking for confirmation, the user can click and select on OK to confirm.
Then again click on the START button and then use the Windows + R button.
In the command prompt, type ‘exe/regserver’ and then click OK
Click on OK again once the confirmation message appears and then confirm if java install error 1601 QuickBooks still persist or not, by installing the software application. If not, then the user needs to download the new version of windows installer.
Solution 4:
The third solution would be to install a diagnostic tool because it resolves the issues caused by various third parties like the .NET framework, MSXML, and C++.
Now, start the system again and sign in as Administrator.
Then open the browser in the PC and browse for QuickBooks Install Diagnostic Tool.
Click on the install Diagnostic Tool Download link and save the file in a local folder.
Then close the background application and double-click on QBInstall_Tool_v2.exe file. Press the Run option.
It will then run a complete scan on the system and repair all the issues.

While the above causes and solutions can act as a medium to repair the issues about the particular error code, the user can also contact QuickBooks Error support, who are available 24*7 for technical assistance.