Multibus plugins and Logic 10.5

When I load a multibus plugin in Logic 10.5 and restrict the supported layouts with isBusesLayoutSupported Logic still shows some layouts that are not supported.

If I add the following method override to examples/Plugins/MultiOutSynthPluginDemo.h

  bool isBusesLayoutSupported(const BusesLayout& layouts) const override {
const auto& outputs = layouts.outputBuses;
auto isStereo16 = std::all_of(std::begin(outputs), std::end(outputs), [](const AudioChannelSet& bus) {
  return bus == AudioChannelSet::stereo();
}) && outputs.size() == 16;

auto isMono = outputs.size() == 1 && outputs[0] == AudioChannelSet::mono();

auto isStereo = outputs.size() == 1 && outputs[0] == AudioChannelSet::stereo();

return isStereo16 || isMono || isStereo;


Then the following layouts are available:


If I select the two first ones the plugin opens. If I select the third one then I get:



I had similar issues in < 10.5 preventing the x25 option where I wanted to only allow x16. But can confirm similar behaviour when only wanting to allow 1 bus!

I think something has gone awry with multi-bus in logic 10.5, i keep seesing this 16x stereo and 25x stereo option on plugins that shouldn’t have that config

Logic 10.5 has suddenly broken all the multiout versions of my plugin… I use to have 5x mono, stereo + 3x mono, and now Logic 10.5 is only listing 16x Stereo etc, and fails to instanciate the plugin if I not choosing 1x mono or 1x stereo.

Has anyone reported an issue to Apple ? [edit: I just wrote to their feedback page]


Do you have a link to that or was it a bug filing report?

I have no link – it’s not a proper bug report: I wrote through


I got a reply from Apple, they say they are aware of the issue and working on a fix, so that’s good news :slight_smile:


Great. Thank you for reporting this to Apple!

Awesome. But I have to say, both with issues I reported to Apple so far, these were the last words I ever heard from them, and it was >2 years ago… but fingers crossed!

I am just a bit bitter with their communication about issue (non-)progress

Does anyone here have any further info on this?

The issue I was having was fixed in version 10.5.1.

Thanks @jpo