Dear you can follow the following step hope you problem will be solved .

Simple Steps to Solved QuickBooks Error 15240

1. Step 1: Run QuickBooks as an Administrator.
2. Step 2: Check & Verify Date/Time Settings. 
3. Step 3: Allow Windows Permission to QuickBooks Folders.
4. Step 4: verify Internet Explorer Settings. 
5. Step 5: Verify your Firewall Settings.
6. Step 6: Reinstall QuickBooks Using Clean Install.

QuickBooks error code 15240 typically occurs when there is an issue with the QuickBooks payroll update or when the update cannot be completed successfully. To resolve error 15240 in QuickBooks, you can follow these steps:

Verify your QuickBooks subscription:

Open QuickBooks and go to the "Help" menu.

Select "QuickBooks Desktop Help" or "QuickBooks Help."

In the search bar, type "Verify Subscription" and select the relevant article.

Follow the instructions provided to verify your subscription.

Check your computer's date and time settings:

Ensure that the date and time on your computer are accurate.

Right-click on the date and time display in the bottom-right corner of your screen (system tray).

Select "Adjust date/time" or "Date and time settings."

Make sure the date, time, and time zone are set correctly. If necessary, adjust them.

Update QuickBooks to the latest release:

Open QuickBooks and go to the "Help" menu.

Select "Update QuickBooks Desktop."

In the "Update QuickBooks" window, click on the "Update Now" tab.

Ensure that the "Reset Update" checkbox is selected.

Click on "Get Updates" to download and install the latest updates.

Once the update process is complete, restart QuickBooks.

Adjust Internet Explorer settings:

Close QuickBooks and open Internet Explorer.

Go to the "Gear" icon (top-right corner) and select "Internet Options."

In the "Internet Options" window, go to the "Security" tab.

Ensure that the security level for the "Internet" zone is set to "Medium-high."

Switch to the "Advanced" tab and scroll down to the "Security" section.

Make sure the following options are checked:

Use SSL 3.0

Use TLS 1.0

Use TLS 1.1

Use TLS 1.2

Click on "Apply" and then "OK" to save the changes.

Configure antivirus and firewall settings:

Temporarily disable or adjust the settings of your antivirus software or firewall.

Refer to your antivirus or firewall documentation or contact their support for instructions on how to add exceptions or allow QuickBooks through the security settings.

Ensure that the following QuickBooks executable files are allowed:

qbw32.exe

qbupdate.exe

qbwebconnector.exe

qbittorrent.exe

Perform a clean installation of QuickBooks:

Uninstall QuickBooks from your computer through the Control Panel.

Download the latest version of QuickBooks from the official Intuit website.

Follow the on-screen instructions to install QuickBooks on your computer.

Greetings,

Peter