I appreciate you for joining here in the thread and bringing this to our attention, @JC745. 

I can see how this has affected your workflow and I'm here to make sure this error gets resolved.

QuickBooks Error 15243 usually happens when Intuit File Copy Service (FCS) is disabled. And is affected by the following:

• When the QuickBooks File Copy Service (FCS) is not working properly
• While the QuickBooks File Copy Service (FCS) is distorted or damaged
• When the update is completed improperly

Let's get started by repairing your QuickBooks Desktop for Windows.

You can also perform the troubleshooting steps that I've listed below to resolve this error. Before diving in, let's make sure that we're using the latest version of QuickBooks and that we've already secured a backup of your company file.
 

First, we'll have to close your QuickBooks, then enable the QuickBooks Desktop File Copy Service:

1. Press Windows+R keys together from keyboard to open Run window.
2. Type COMPMGMT.MSC then click OK.
3. Select Services and Applications, then click Services.
4. Scroll down then double-click Intuit QuickBooks FCS.
5. Click on Startup type and choose Manual.
6. Then click Apply then OK.

Once done, re-validate the payroll's service key to refresh the connection:
 

1. Select Employees from the top menu bar.
2. Choose My Payroll Service.
3. Select Activate Service Key. 
4. Click Edit from the Service Keys window
5. Hit Next, then wait until the process is done.

For additional reference, here's an article that'll help you utilize our QuickBooks Tool Hub to fix common issues: Fix common problems and errors with the QuickBooks Tool Hub.

Fill me in if you need additional assistance while performing the recommended steps. I'm always happy to help. Keep safe.