We'll also have to take note that -6000 errors can happen on both local and network setup. If you're opening the file locally. We can start by renaming the .ND and .TLG files. These are configuration files that allow QuickBooks to access a company file in a network or multi-user environment. If these files are corrupted or damaged, you will encounter these errors when you open your QuickBooks files. Here's how:
Open the folder that contains your company file.
Find the files with the same file name as your company files but with extensions .ND and .TLG.
Right-click each file and select Rename. Add the word OLD at the end of each file name.Example: company_file.qbw.nd.OLD
Open QuickBooks again and try to sign in to your company file.
If the same issue occurs, we can open a sample company file to check if the problem possibly lies with your company file or the QuickBooks application. You can follow the steps below:
In the No Company Open window, select Open a Sample File and choose any from the list of sample company files.