[CBT-2120] Reproducible crash with AU plugins and background audio

Hi! I found a repeatable crash with Cubasis 3, these are the details:


  1. Open Cubasis
  2. Create a new empty project
  3. Add a MIDI track
  4. Switch to an AU instrument
  5. Open the UI for the instrument
  6. Switch to another app, leaving Cubasis in the background
  7. Cubasis crashes within 15 seconds (red mic icon disappears)

Additional details:

  • The crash doesn’t happen if I don’t switch to another app
  • The crash doesn’t happen if background audio is disabled
  • The crash doesn’t happen if the AU UI is minimized when Cubasis is moved to the background
  • The crash happens with or without “Studio quality” enabled
  • The crash happens whether the device is being charged or not
  • The crash happens with or without external audio interfaces plugged in
  • The crash doesn’t happen with built-in instruments or effects
  • The crash also happens with AU effects
  • The crash happens with multiple vendors (I tried Nikolozi, Burns Audio, Audio Damage, ToneBoosters and others)
  • The crash doesn’t happen with AUM or NanoStudio 2 using comparable steps
  • The crash happens in iPadOS 14.0 (iPad Pro 12.9" 3rd gen), iPadOS 13.7 (iPad 5th gen) and iOS 14.0 (iPhone XR)
  • The crash logs all say some variation of “9 seconds cpu time over 11 second (84% cpu average), exceeding limit of 60% cpu over 15 seconds”

Let me know if you’d like me to send the same information somewhere else. Thanks!

Same here. 2019 iPad iOS 14

Hi NoiseFloored,

Thank you for your message, we are able to reproduce the problem.

Known issue
Cubasis 3.1.3 is terminated by iOS 14 if it is sent to the background with an Audio Unit’s UI open and the Background Audio setup option enabled.

Close any Audio Unit UIs (effect rack, instrument rack) before switching to the home screen or another app.

The issue will be addressed in the next Cubasis update.


Planned to be fixed in the upcoming update!