Set up all settings manually by renaming the .nd and .tlg files
When the .nd and .tlg files become corrupt due to some reason, it could result in QuickBooks 6123 error. A simple solution to fix this issue is to rename these files. There is no harm in renaming these files as it does not cause any data loss. In fact, when you use the QuickBooks Database Server Manager to re-scan, these files will be automatically created.
Here are the steps to rename the .nd and .tlg files.
1- Navigate to the folder having your company file
2- In the next step you have to search for files with extension .nd and .tlg. Make sure these files have the same names as your company files, such as:
(company name _file).qbw.nd
(company name _file).qbw.tlg
3- Now, right-click the files and select the Rename option
4- To differentiate files, add “OLD” or any other word of your choice at the end of the file. Remember you have to add the word to the extension and not the file name.
(company name _file).qbw.nd.OLD
(company name _file).qbw.tlg.OLD
5- Open QuickBooks and sign in to your company file.