With technical things you never know what error is going to come next. QuickBooks Error 6000 shows up when everything seems to work fine but you try to open up the Company file. It could occur because of numerous reasons. Here is a list of few possibilities that might help you to identify the cause of this issue.
The files with extension .TLG got corrupted
QB installation failed
The error might be a result of firewall restriction
Corrupt company file
Many people are accessing the company file
However, it can be easily resolved with immediate assistance from the QB technical support team. In case you have any queries, drop us a msg and we will revert you back.
https://www.quickbooksphonenumber.com/blog/fix-quickbooks-error-6000/