What is QuickBooks Error 6000?

https://quickbookhelpdesk.com/blog/quickbooks-error-6000-when-opening-company-file/

QuickBooks Error 6000 can prevent you from opening a company file because of problems with the file, network, folder permissions, hosting settings, or QuickBooks installation. Start by updating QuickBooks and running QuickBooks File Doctor. If the problem continues, rename the .ND and .TLG files, test a sample company file, and try opening a copy of your company file from the desktop.