The error "Result code= -48" is simply a duplicate file name error. Toast temporarily stores its disc projects in Documents > Roxio Converted Items. Sometimes, the disc projects that you try to burn may have titles that are duplicates of what you have stored in the Roxio Converted Items folder.
Note: This procedure applies to all versions of Toast
But they may also be located elsewhere. The following sections will provide you some information on where to look for these duplicate files.
Locate duplicate files
If you have not tried checking your file folders yet (e.g. Pictures, Music, Movies, Documents), please do now and see if there is another file that has the same name as your current DVD project. If you see one, isolate the file or delete it, if possible.
Reboot your Mac
Temporary files are supposedly deleted after Toast uses them. In rare cases, these files do not get deleted due to some temporary glitch. Maybe your Mac computer simply needs some encouragement to delete said files. You can do this by performing a reboot.
If the error still comes up after doing a reboot, those duplicate files may be stored elsewhere in your system.
Deleting the system cache
As a rule, cached files are temporary files that you can safely get rid of. There are times, however, that some of these temporary files do help your system to function optimally. So before you dive in and go zapping those cached files, make sure you back up your system first so you have the ability to restore your important files if everything goes awry.
Here is how to access the system cache files in macOS in case you want to go look there:
1. Open Finder. From the Go menu, select Go to Folder...
2. A dialog box will pop up. Type in ~/Library/Caches/ and then click the Go button.
3. Your system, or library, caches folder will come up.
4. Go through the list of folders and see if there is anything that has “Roxio”, “Sonic” (or “Sonic1”, “Sonic2”, etc.) or “Toast” in the name, e.g., “roxio.toast”. You can either go into each folder that you find and look for duplicates; or just rename that folder to something else. So, for instance, you can rename “com.roxio.toast” to “com.roxio.toast_old”. This essentially makes the folder invisible to Toast, and it will no longer access that cache folder but will create a fresh one. If renaming any of these folders cause problems with Toast later on, you can simply go back and revert to the original folder name, so make sure you are taking notes.
A disc image file may be in use
It is also possible that the duplicate file is currently being used - an example is if the duplicate is an ISO disc image file, and it is currently mounted. If you are trying to create a newer version of the ISO file and have given it the same name as the existing one, Toast will be unable to overwrite it and make the necessary changes since it is in use, and so an error “Result code = -48” will come up. Unmount the image file and rename it.
Create a new user account
If all else fails, create a new Admin account and sign in to it, reinstall Toast, then try your project there. Of course you will need to make the files you will be using available to the other user account. Here's how if you need instructions. The new user account is only for isolating the problem. If you are able to complete your project successfully under the new user account, this will confirm that the cause of the problem exists somewhere in your main account. Please open a support ticket here.