Hello ituck,
Thanks for reaching out to us here. Welcome! I can see how the error you've mentioned can cause concern, when trying to work in multi-user mode with QuickBooks Desktop. I would be happy to provide some insight here!
The error you've mentioned, can occur on both local and network setup, stating you cannot open your company file. Error -6190, 816 indicates 'A user is in single user mode instead of multiuser while they work in the file.
It can be a mismatch between the transaction log file (.tlg) and the company file (.qbw)', as noted here.
Should you require additional assistance, please don't hesitate to contact our QuickBooks Desktop Customer Care team outside of Community. They would enjoy the opportunity to work with you personally, and ensure you're back to business as soon as possible!
Feel free to touch base with us again, if you have other questions or concerns. We would be glad to help!
