Certain word orders on Adachi Rei -English- with CLASSIC renderer break renderer

[4dTailor]

Acknowledgement

• I have read Getting-Started and FAQ
• If dealing with version 0.1.549 or higher, you have installed the .NET 8 runtime

🐛 Describe the bug

When trying to play a song using Adachi Rei -English- on the CLASSIC renderer with the default EN C+V phonemiser, the program throws an error, and the audio won't play. The program won't crash, but trying to play it again throws the same error.

Explains how to reproduce the bug

1. Download & Install OpenUtau v0.1.568.0 (beta)
2. Install Adachi Rei -English- from https://adachi-rei.carrd.co/#download
3. Create track with Adachi Rei -English- as singer
4. Set phonemiser to EN C+V
5. Set renderer to CLASSIC
6. Place BPM at 190
7. Place notes:
   quarter note A#3 - "i"
   eighth note C#4 - "wish"
8. Play song
9. Error below appears, and render fails:

Failed to render.
One or more errors occurred. (One or more errors occurred. (Index was outside the bounds of the array.))

System.AggregateException: One or more errors occurred. (One or more errors occurred. (Index was outside the bounds of the array.))
 ---> System.AggregateException: One or more errors occurred. (Index was outside the bounds of the array.)
 ---> System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at OpenUtau.Classic.SharpWavtool.Concatenate(List`1 resamplerItems, String tempPath, CancellationTokenSource cancellation) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\SharpWavtool.cs:line 42
   at OpenUtau.Classic.ClassicRenderer.<>c__DisplayClass8_0.<RenderInternal>b__0() in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\ClassicRenderer.cs:line 89
   at System.Threading.Tasks.Task`1.InnerInvoke()
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at System.Threading.Tasks.Task.Wait()
   at OpenUtau.Core.Render.RenderEngine.RenderRequests(RenderPartRequest[] requests, CancellationTokenSource cancellation, Boolean playing) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Render\RenderEngine.cs:line 235
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
   --- End of inner exception stack trace ---

0.1.568.0

8. USTX here: Bug.zip

OS & Version

Windows 11 Home 25H2

Logs

2026-06-21 15:04:19.274 +10:00 [INF] Logging initialized.
2026-06-21 15:04:19.302 +10:00 [INF] Microsoft Windows NT 10.0.26200.0
2026-06-21 15:04:19.303 +10:00 [INF] Microsoft Windows 10.0.26200 X64 X64
2026-06-21 15:04:19.304 +10:00 [INF] OpenUtau v0.1.568.0 win-x64
2026-06-21 15:04:19.304 +10:00 [INF] Data path = C:\Users\dank\Documents\OpenUtau
2026-06-21 15:04:19.304 +10:00 [INF] Cache path = C:\Users\dank\Documents\OpenUtau\Cache
2026-06-21 15:04:19.305 +10:00 [INF] System encoding = utf-8
2026-06-21 15:04:19.541 +10:00 [INF] Initializing application.
2026-06-21 15:04:19.580 +10:00 [INF] Initializing culture.
2026-06-21 15:04:19.583 +10:00 [INF] Initialized culture.
2026-06-21 15:04:19.583 +10:00 [INF] Initializing theme.
2026-06-21 15:04:19.589 +10:00 [INF] Initialized theme.
2026-06-21 15:04:19.589 +10:00 [INF] Initialized application.
2026-06-21 15:04:19.589 +10:00 [INF] Framework initialization completed.
2026-06-21 15:04:19.693 +10:00 [INF] Initializing OpenUtau.
2026-06-21 15:04:19.694 +10:00 [INF] Searching singers.
2026-06-21 15:04:19.747 +10:00 [INF] Search all singers: 00:00:00.0522842
2026-06-21 15:04:19.760 +10:00 [INF] Search all plugins: 00:00:00.0117381
2026-06-21 15:04:19.761 +10:00 [INF] Search all legacy plugins: 00:00:00.0002351
2026-06-21 15:04:19.761 +10:00 [INF] Initialized OpenUtau.
2026-06-21 15:04:19.761 +10:00 [INF] Initializing audio.
2026-06-21 15:04:19.762 +10:00 [INF] ReleaseSourceTemp C:\Users\dank\Documents\OpenUtau\Cache
2026-06-21 15:04:20.452 +10:00 [INF] Initialized audio.
2026-06-21 15:04:20.456 +10:00 [INF] Creating main window.
2026-06-21 15:04:20.511 +10:00 [INF] Initialized main window component.
2026-06-21 15:04:20.563 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:20.586 +10:00 [INF] Publish notification Load project
2026-06-21 15:04:20.591 +10:00 [INF] Main window checking Update.
2026-06-21 15:04:20.592 +10:00 [INF] Created main window.
2026-06-21 15:04:20.658 +10:00 [INF] Attach singer to track: AdachiRei_EN
2026-06-21 15:04:20.667 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:20.694 +10:00 [INF] Publish notification Load project
2026-06-21 15:04:20.696 +10:00 [INF] undoGroup started
2026-06-21 15:04:20.696 +10:00 [INF] undoGroup ended
2026-06-21 15:04:20.697 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:20.697 +10:00 [INF] Publish notification Pre-render notification.
2026-06-21 15:04:20.697 +10:00 [INF] Publish notification Voice color remapping.
2026-06-21 15:04:20.868 +10:00 [INF] Checking update at: https://github.com/openutau/OpenUtau/releases/tag/0.1.568
2026-06-21 15:04:20.869 +10:00 [INF] Checking appcast: https://github.com/openutau/OpenUtau/releases/download/0.1.568/appcast.win-x64-installer.xml
2026-06-21 15:04:21.047 +10:00 [INF] Publish notification Phonemized
2026-06-21 15:04:22.969 +10:00 [INF] undoGroup started
2026-06-21 15:04:23.022 +10:00 [INF] undoGroup ended
2026-06-21 15:04:23.022 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:23.022 +10:00 [INF] Publish notification Pre-render notification.
2026-06-21 15:04:23.093 +10:00 [INF] undoGroup started
2026-06-21 15:04:23.157 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.161 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.162 +10:00 [INF] Publish notification Select expression pitd
2026-06-21 15:04:23.182 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.183 +10:00 [INF] Publish notification Select expression clr
2026-06-21 15:04:23.184 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.184 +10:00 [INF] Publish notification Select expression eng
2026-06-21 15:04:23.185 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.185 +10:00 [INF] Publish notification Select expression vel
2026-06-21 15:04:23.186 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.186 +10:00 [INF] Publish notification Select expression vol
2026-06-21 15:04:23.186 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.187 +10:00 [INF] Publish notification Select expression atk
2026-06-21 15:04:23.187 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.187 +10:00 [INF] Publish notification Select expression dec
2026-06-21 15:04:23.188 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.188 +10:00 [INF] Publish notification Select expression gen
2026-06-21 15:04:23.188 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.189 +10:00 [INF] Publish notification Select expression bre
2026-06-21 15:04:23.222 +10:00 [ERR] undoGroup already started
2026-06-21 15:04:23.222 +10:00 [INF] undoGroup ended
2026-06-21 15:04:23.222 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:23.223 +10:00 [INF] Publish notification Pre-render notification.
2026-06-21 15:04:23.223 +10:00 [INF] undoGroup started
2026-06-21 15:04:23.223 +10:00 [INF] undoGroup ended
2026-06-21 15:04:23.223 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:23.223 +10:00 [INF] Publish notification Pre-render notification.
2026-06-21 15:04:23.224 +10:00 [INF] undoGroup started
2026-06-21 15:04:23.224 +10:00 [INF] undoGroup ended
2026-06-21 15:04:23.224 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:23.224 +10:00 [INF] Publish notification Pre-render notification.
2026-06-21 15:04:23.636 +10:00 [INF] Created bitmap 794, 60
2026-06-21 15:04:23.680 +10:00 [WRN] Validate Project not on main thread
2026-06-21 15:04:23.680 +10:00 [WRN] Pre-render notification. not on main thread
2026-06-21 15:04:23.706 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.706 +10:00 [INF] Publish notification Select expression pitd
2026-06-21 15:04:23.707 +10:00 [INF] Publish notification Select expression clr
2026-06-21 15:04:23.708 +10:00 [INF] Publish notification Select expression eng
2026-06-21 15:04:23.708 +10:00 [INF] Publish notification Select expression vel
2026-06-21 15:04:23.709 +10:00 [INF] Publish notification Select expression vol
2026-06-21 15:04:23.709 +10:00 [INF] Publish notification Select expression atk
2026-06-21 15:04:23.709 +10:00 [INF] Publish notification Select expression dec
2026-06-21 15:04:23.710 +10:00 [INF] Publish notification Select expression gen
2026-06-21 15:04:23.710 +10:00 [INF] Publish notification Select expression bre
2026-06-21 15:04:23.726 +10:00 [INF] Publish notification Load part
2026-06-21 15:04:23.726 +10:00 [INF] Publish notification Select expression pitd
2026-06-21 15:04:23.726 +10:00 [INF] Publish notification Select expression dyn
2026-06-21 15:04:23.812 +10:00 [INF] Publish notification Validate Project
2026-06-21 15:04:23.812 +10:00 [INF] SchedulePreRender
2026-06-21 15:04:23.812 +10:00 [INF] Publish notification Pre-render notification.
2026-06-21 15:04:23.814 +10:00 [ERR] No active undoGroup to end.
2026-06-21 15:04:23.828 +10:00 [INF] Publish notification Phonemized
2026-06-21 15:04:24.033 +10:00 [ERR] Failed to pre-render.
System.AggregateException: One or more errors occurred. (Index was outside the bounds of the array.)
---> System.IndexOutOfRangeException: Index was outside the bounds of the array.
at OpenUtau.Classic.SharpWavtool.Concatenate(List1 resamplerItems, String tempPath, CancellationTokenSource cancellation) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\SharpWavtool.cs:line 42 at OpenUtau.Classic.ClassicRenderer.<>c__DisplayClass8_0.<RenderInternal>b__0() in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\ClassicRenderer.cs:line 89 at System.Threading.Tasks.Task1.InnerInvoke()
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
at System.Threading.Tasks.Task.Wait()
at OpenUtau.Core.Render.RenderEngine.RenderRequests(RenderPartRequest[] requests, CancellationTokenSource cancellation, Boolean playing) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Render\RenderEngine.cs:line 235
at OpenUtau.Core.Render.RenderEngine.<>c__DisplayClass8_0.b__0() in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Render\RenderEngine.cs:line 165
2026-06-21 15:04:25.368 +10:00 [INF] StartPlayback at 00:00:00
2026-06-21 15:04:25.370 +10:00 [ERR] Failed to render.
System.AggregateException: One or more errors occurred. (Index was outside the bounds of the array.)
---> System.IndexOutOfRangeException: Index was outside the bounds of the array.
at OpenUtau.Classic.SharpWavtool.Concatenate(List1 resamplerItems, String tempPath, CancellationTokenSource cancellation) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\SharpWavtool.cs:line 42 at OpenUtau.Classic.ClassicRenderer.<>c__DisplayClass8_0.<RenderInternal>b__0() in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\ClassicRenderer.cs:line 89 at System.Threading.Tasks.Task1.InnerInvoke()
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of inner exception stack trace ---
2026-06-21 15:04:25.425 +10:00 [INF] Publish notification Error message: Failed to render. System.AggregateException: One or more errors occurred. (One or more errors occurred. (Index was outside the bounds of the array.))
---> System.AggregateException: One or more errors occurred. (Index was outside the bounds of the array.)
---> System.IndexOutOfRangeException: Index was outside the bounds of the array.
at OpenUtau.Classic.SharpWavtool.Concatenate(List1 resamplerItems, String tempPath, CancellationTokenSource cancellation) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\SharpWavtool.cs:line 42 at OpenUtau.Classic.ClassicRenderer.<>c__DisplayClass8_0.<RenderInternal>b__0() in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Classic\ClassicRenderer.cs:line 89 at System.Threading.Tasks.Task1.InnerInvoke()
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
at System.Threading.Tasks.Task.Wait()
at OpenUtau.Core.Render.RenderEngine.RenderRequests(RenderPartRequest[] requests, CancellationTokenSource cancellation, Boolean playing) in D:\a\OpenUtau\OpenUtau\OpenUtau.Core\Render\RenderEngine.cs:line 235
at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of inner exception stack trace ---
2026-06-21 15:04:32.113 +10:00 [INF] Exiting.
2026-06-21 15:04:32.114 +10:00 [INF] Exited.

[4dTailor]

Through some basic testing, I believe it's something with the ay phoneme, though setting the "I" note to C#4 or D4 doesn't cause the error.

[nagotown]

Are you using worldline (not WORLDLINE-R) or another resampler?

[4dTailor]

I presume so, as though the renderer under the Singer section says CLASSIC and the resampler engine for the notes is not set, I only have worldline as an option for the resampler engine, and the bottom row that reports the phonemes says stuff like Track 1: worldline "w".

[4dTailor]

i've found where the resampler settings are, and can say for certain that it's using the worldline resampler, and the convergence wavtool

[4dTailor]

With that, i've also noticed that the renderer crashes when setting resampler to worldline and setting wavtool to convergence or simple - setting wavtool to moresampler doesn't cause the crash.

[BagelHero]

This is a bug to do with either the oto.ini parameters of the vocal being too close together, or the overlap being longer than the preutterance value within a quick succession of phonetics causing the envelope to become invalid/twisted. This is pretty common in C+V voicebanks due to their structure.

Even though this is technically a configuration "error", I believe between this PR, and this one it should be fixed in the dev branch/"nightly" soon. No current release schedule for the beta release though, so in the meantime yes different resamplers and wavtools may mute the error dialog.