In order to re-establish a connection with the FM Books Connector properly, there are specific steps that need to be followed:
1) Open Quickbooks and log into the company file that you want to establish a connection to with an admin account in single-user mode
2) From the “Edit” menu, click on “Preferences”, click on “Integrated Applications” and in the “Company Preferences” tab remove any instances of FMBooks Connector and click OK.
3) Close FileMaker.
4) Go to C:\Users\<current user>\AppData\Local\PCINC
5) Delete the folder called FMBCONNECT
6) Open the demo file provided with the FM Books Connector plug-in
7) Enter your License ID and click “Register”
8) With both Quickbooks and FileMaker open, click on “Test”
9) Quickbooks will prompt about making a connection with FileMaker. Choose your desired connection type and click “Continue...”