Situation

CountIt v2.4.0 has been in use for several years with a QuickBooks version older than 2018.

After QuickBooks is updated to version 2018, CountIt is able to retrieve inventory from QuickBooks, but when clicking View/Reconcile there is a message "Failed to connect to QuickBooks. Please make sure QuickBooks connects to your company data."

CountIt's log file reports this error:
2018-12-28 11:22:39.694          1 INFORMATION | The highest version of XML that the currently connected QuickBooks running is 13
2018-12-28 11:22:39.694          1 ERROR       | System.Runtime.InteropServices.COMException (0x8004030A): Unsupported qbXML version.

Wasp CountIt shows in QuickBooks as an integrated application. The connector was repaired.

Resolution

Update CountIt to v2.4.1:
http://dl.waspbarcode.com/wasp/WaspCountIt_Installer_2_4_1.exe