When you try to open a company file then you might have fallen prey to QuickBooks error 6150. There is not just 1 reason behind this but several of them.
The most common one is that your company file might be corrupted and to overcome it, you will be needed to create a portable backup file before trying to fix the problem.
We need to create a backup file because if something goes wrong then you should have a backup file to fall back to. It could have also happened if you tried to install QuickBooks and the process got corrupted.