# ArpeggiatorTutorial not working as VST3 - BUG?

**URL:** <https://forum.juce.com/t/arpeggiatortutorial-not-working-as-vst3-bug/57244>\
**Category:** General JUCE discussion\
**Created:** [July 31, 2023, 6:25pm UTC](https://forum.juce.com/t/arpeggiatortutorial-not-working-as-vst3-bug/57244 "2023-07-31T18:25:32Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![RagsInRags](https://avatars.discourse-cdn.com/v4/letter/r/34f0e0/32.png) [@RagsInRags](https://forum.juce.com/u/RagsInRags)\
**Post date:** [July 31, 2023, 6:25pm UTC](https://forum.juce.com/t/arpeggiatortutorial-not-working-as-vst3-bug/57244/1 "2023-07-31T18:25:32Z")

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I am struggling to handle Midi events in processBlock of a VST3. The processBlock code executed without error, however, Ableton seems to bypass all the processing and just transfer the input midi messaged onto the output. After multiple attempts, I finally went back to basics.

1. I downloaded the demo source code for the Arppegiator tutorial from here - [JUCE: Tutorial: Plugin examples](https://docs.juce.com/master/tutorial_plugin_examples.html#tutorial_plugin_examples_arpeggiator)

2. Compiled the code and tried to load it up as a VST3 in Abelton. Abelton gave an error

3. Updated the projucer project properties to set `Plugin is a synth`,`Plugin MIDI Input`,`Plugin Midi Output` and removed `Midi Effect Plugin`.

4. Now my plugin showed in Ableton, but it was not working

5. Ran the code in standalone mode. It was working !

6. Went back to VST3 plugin and In VS2022, put a debug point in `processBlock`. the line: `jassert(buffer.getNumChannels() == 0)` was failing. I am assuming that since the plugin was marked as a synth, this behaviour should be expected. So I commented this line.

I am now stumped. I tied reading various posts on how to make a VST3 Midi plugin and believe the issue should be only with receiving MIDI CCs. Note messages should work fine. So I am no longer sure what is the correct way to create a Midi handling VST3 plug-in with JUCE. I am using JUCE 7.

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<div class="post-metadata">

**Author:** ![RagsInRags](https://avatars.discourse-cdn.com/v4/letter/r/34f0e0/32.png) [@RagsInRags](https://forum.juce.com/u/RagsInRags)\
**Post date:** [August 1, 2023, 8:39am UTC](https://forum.juce.com/t/arpeggiatortutorial-not-working-as-vst3-bug/57244/2 "2023-08-01T08:39:33Z")

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OK. Did some more digging and found a good thread [VST3 (midi) and JUCE - Audio Plugins - JUCE](https://forum.juce.com/t/vst3-midi-and-juce/31100/21?page=2).

Updated the Projucer properties to UNCHECK `Plugin isa synth`, and CHECK `Plugin MIDI Input` along with `Plugin MIDI Output`. This now works.