Multi User Mode not recognized

Thanks for reaching out to the Community, klavant. I appreciate your detailed information.

If you're encountering error codes 6190 and 816, they indicate that another user has signed in to the company file in single-user mode, preventing you from opening it. 

To resolve this, that user will need to switch from single-user to multi-user mode. After doing so, you won't encounter the error messages.

In the event you're encountering these errors while all users are in multi-user mode, I'd recommend getting in touch with our Customer Care team. They'll be able to pull up your account in a secure environment, conduct further research with you, and create an investigation ticket if necessary.

They can be reached while you're signed in.

Here's how:
 

1. Open QuickBooks.
2. In the top menu bar, go to Help, then QuickBooks Desktop Help/Contact Us.
3. Enter a question, keyword, or topic you need help with.
4. Select Contact Us.

Be sure to review their support hours so you'll know when agents are available.

If there's any additional questions, I'm just a post away. Have a wonderful Wednesday!