File format is invalid

Hi Alohatutu,

You mentioned opening a CD, is this a Music disc you're trying to play?

If you're trying to playback a CD, take these steps:

1. In the Music app  on your Mac, choose Music > Preferences, click General, then click the “When a CD is inserted” pop-up menu and choose Play CD.

2. Insert an audio CD into your computer’s CD or DVD drive, or into an external drive that’s connected to your computer.

The CD begins to play. If you don’t see information for the CD, select the CD under Devices in the sidebar.

Play CDs in Music on Mac

Let us know if those are the steps you're taking.

Thanks for using the Apple Support Communities.

What is telling you this? macOS? The Finder? Some app?

What type of CDs?

Are these CDs containing data or "media" from the factory? Or are these CDs someone has created themselves by "burning" the data to the CD? Burned CD media do degrade over time so the data may now be corrupt. Also, how were they created and on what type of computer & OS? Recent versions of macOS may have trouble reading some very old discs depending on the formats used.

Or the CDs are dirty or scratched, or maybe the optical drive is dirty or even has failed. Try using a cleaning disc to clean the lense of optical drive, or try using another optical drive.