It would appear that there may be a conformed audio file involved here.
Have you updated 12 to 12.1 yet? If not, please do that.
Go to Edit Menu/Preferences/Scratch Disks, and determine where the Media Cache category is pointed. Go to that Media Cache Files Folder at that location, and delete the content of the Media Cache Files Folder (cfa and pek files....)
The program will generated new cfa and pek (conformed audio) files when and if it decides that they are needed.
What specifically were you doing in the program when you obtained this error? If in a burn to disc, at what phase of the burn to - Encoding menu, Encoding Media, Compiling Media, Burn disc?
Do you have source media .m2ts video linked with audio files that you imported into your project? When you import the source media for the Timeline, do you wait for any video and/or audio conforming to complete before you move forward in the project? See progress bar at the bottom right of the workspace to view such activities if they are going on.
Please review and consider. We will decide what next based on the details in your reply.