When attempting to establish a new company file, QuickBooks Error 6129 arises because the database verification failed. Corrupted Network Data (.ND) files, restricted folder permissions, mismatched domains in a multi-user setup, or QuickBooks being blocked by antivirus software can all cause this problem. You can fix it by running QuickBooks File Doctor, renaming the.ND file, changing security settings, temporarily turning off antivirus software, or creating a new Windows user with administrator privileges.