Facing an error is quite common while working on any software. However, that frustrates a lot when it appears with QuickBooks accounting software. A similar situation happens when a user faces QuickBooks error 6000 which occurs due to corrupted TLG file, damaged QuickBooks installation file, damaged company fine, firewall blocking the QuickBooks server connection, the multiple users might have logged in with the same company file or the network connection is incorrectly configured. To eliminate the problem you will need to first restore the backup and re-configure the firewall and antivirus software to mark QuickBooks files as a genuine application. Another fix could be opening the company files in another location or renaming the TLG and ND files by adding OLD at the end of the name.