There is an error in the log similar to this:
This error comes directly from the Intuit Software Development Kit (SDK) and indicates that it does not have permissions from the requested QuickBooks file to communicate with it.
There are two possible causes for this error:
1. The QB file has not assigned permissions for allowing QQube to connect - or they have been removed/revoked.
This can happen if the users and permissions are not created and assigned per our create connection users guide, but more often then not, it happens because someone replaced the existing QB file, with one that never had the permissions assigned.
2. You have more than one QQube Synchronizer running on the server or workstation. Invoke taskmgr.exe to see if qqubesynchronizer.exe is running (or check the user's startup folder) for users:
Cause 1. Ensure that QuickBooks contains the following entry under Integrated Applications:
If it doesn't show like this, then you may need to re-establish the permissions between QuickBooks and QQube, by removing the company from QQube, and then re-adding the company in the same step, per the steps in this guide: https://clearify.com/wiki/view/3310/add-a-quickbooks-company-file
Cause 2. There are several reasons why this would have occurred.
What happens in either of these cases is that you have more than one synchronizer running, thus confusing the QQube synch process.
To fix the first possible reason under Cause 2, you need to uninstall from the person who originally installed QQube under their name - ensuring that they have administrative rights for the uninstall process (do not right click and "Run as Administrator") Then reinstall under the either the dedicated synch user in a multi-user environment, or the desired user on a workstation in a single-user environment. See https://clearify.com/wiki/view/157/installation
To fix the second possible reason for Cause 2, you need to do two things: (Only for versions earlier than 7.x)
is requesting access to a wiki that you have locked: https://clearify.com/wiki/view/3692/error-80040418-quickbooks-permissions-missing