When QuickBooks integration manager (QBi) is launched, and it tries to connect to QuickBooks, it shows a message stating: Integration Manager could not connect to QuickBooks. Please make sure that it is open. In Application section of the event viewer in Windows, it shows an error message which states: Quick books EventID 4 – An unexpected error has occured in "QuickBooks": Returning NULL QBWinInstance Handle.QuickBooks event log error 4 is mainly caused by .NET Framework 4.0 SP 1 problems if you are using the Microsoft Windows 7 OS.If the error persists then you can call the QuickBooks support number and ask for additional assistance. Professional software experts are available 24 hours a day and will be able to give a step-by-step guide so that you can solve <a href="https://247quickbooks.com/resolving-quickbooks-event-id-4-unexpected-error-5/">quickbooks event id 4 error</a> as soon as possible.