Your Walkman is not recognized as USB storage.

  • The USB connection is turned off.

  • If your Walkman is in MSC mode, swipe the status bar, then tap [Turn on USB storage] on the notification panel followed by [Turn on USB storage] then [OK].

  • USB debugging is enabled.

  • Some devices or software may not recognize your Walkman when USB debugging is enabled. Tap the (Menu) button, then tap [System settings] - [ Developer options] - [USB debugging] and uncheck the box.