The QuickBooks Error 6000 is one of the most common QuickBooks errors experienced by users when accessing some company files. The error can occur due to various reasons: First: the company file is located on external storage; Second: incorrect folder permission which contains a company file; or the third: the company file is opened with a reference from a mapped drive. 1. TLG file corrupted 2. Corrupted QuickBooks installation file 3. A firewall is blocking the connection 4. Damaged company file 5. Multiple users logged in to the same company file 6. The network connection is incorrectly configured.