I was troubleshooting error -6123, 0 with QuickBooks Pro 2008, finally solved the problem and thought I'd share.
text of this error message was something to the effect of "cannot
connect to database server," however, mine was a single user
installation with the company file residing locally. I realize
QuickBooks may use a database server to connect to even a local
database, but the knowledge base article on Intuit's website for error -6123, 0
was aimed at situations that did not apply to me. I was not using the
company file over the network, I was not in multi-user mode, nor was I
restoring a backup.
I went through a bunch of things,
including the use of the QuickBooks File Doctor, which said my database
was perfect. I disabled Windows firewall, and was using no other. I
restored a backup of the company file using Windows Previous Versions. I
checked QuickBooks services but found nothing that jumped out at me. I
I started thinking about how I
had the system set up. The computer is joined to a domain, so I logged in
as Domain Administrator, tested QuickBooks, and it worked. The user I
have set up to use QuickBooks doesn't have local admin, and I'd rather
avoid giving it to her if possible. So I started Googling and ended up
finding another Intuit knowledge base article for "Configuring multi-user access requires Windows Admin rights". Even though I'm not in a multi-user scenario, I decided to see if the information was helpful anyway, and it turns out it was.
Solution: For QuickBooks Pro 2008, there is a Windows user account called
"QBDataServiceUser18" which I added to the local Administrators
group. That did the trick and now my user can access QuickBooks without
that pesky error anymore, and without admin rights!