You see an error in the log similar to this:
This error comes directly from the Intuit Software Development Kit (SDK) and indicates that it is unable to open the requested QuickBooks company file because it is "not clear" to do so.
There are only eight possible causes:
Cause 1. The QuickStart feature allows QuickBooks to be 'always running' but causes communication errors, and must be turned off. This is NOT a global preference - and why you login as the QQube User to ensure its effect.
Cause 2. This usually happens when someone remotely logs in and needs to perform an 'Administrator' only task, requiring single user mode, to merge accounts, items. Etc. Just requires awareness.
Cause 3. This can occur if you did not choose the specific QQube user to automatically open the QuickBooks file, and the user you did choose, is being logged into elsewhere. This can also occur with an incorrect setup in a Remote Desktop / Terminal Services environment where several users are set to be the Synchronizer Computer on the server. (See Cause 8. below.)
Cause 4. You can either change the QuickBooks company file name back to what was previously listed in the QQube Configuration Tool, or Add/Remove Company to reset the correct name. (You can't change the name of the company in the QQube Configuration Tool Directly). If you have a multi-user version you can only do this on the server.
Cause 5. Use the QQube Configuration Tool to change the path. If you have a multi-user version you can only do this on the server.
Cause 6. Open up QuickBooks to NO company file, before attempting to load multiple QuickBooks files. The Software Development Kit (SDK) does not allow developers to close a QuickBooks file that is already manually opened.
Cause 7. The key to fixing this error, is understanding and acknowledging the concept of having a dedicated, always running, server user that does nothing but allow the QuickBooks client and the QQube Database to communicate. Please review the installation and requirements guides.
Cause 8. 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 8, you need to uninstall from the person who orignally installed QQube under their name - ensuring that they have administrative rights for the uninstall process (do not right click and "Run as Adminstrator") 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 8, 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/381/error-80040408-quickbooks-doesn-t-start