The above error is generated when one or more MIDI Devices cannot be enabled. This error generally occurs when the MIDI device driver is in use by another application.
1. Ensure that you don't have any other applications open which may be utilizing your MIDI driver.
2. Reboot your computer to ensure that the MIDI driver isn't stuck within a background process or application that previously accessed the driver.
Google Chrome Users
Google Chrome has the ability to access your MIDi device drivers, so you may encounter this error while using Google Chrome. You can do the following to disable MIDI access from Google Chrome:
1. In chrome navigate to 'Settings > Advanced Settings > Content Settings'.
2. Locate the 'MIDI devices full control' section.
3. Enable the 'Do not allow any sites to use system exclusive messages to access MIDI devices' option.
Image-Line Support Team