[BUG] searching for MFA dict

[nrgslp]

Problem

I received this traceback during first-time use. This is a new MFA env for me, that I set up to test VoxKit.

An error occurred:
Dictionary 'english_us_arpa' is not available. Download failed with: Traceback (most recent call last):
File "C:\ASU\miniconda3\envs\aligner\Scripts\mfa-script.py", line 5, in
from montreal_forced_aligner.command_line.mfa import mfa_cli
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner_init_.py", line 4, in
import montreal_forced_aligner.acoustic_modeling as acoustic_modeling
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\acoustic_modeling_init_.py", line 7, in
from montreal_forced_aligner.acoustic_modeling.base import AcousticModelTrainingMixin # noqa
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\acoustic_modeling\base.py", line 20, in
from montreal_forced_aligner.alignment import AlignMixin
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\alignment_init_.py", line 6, in
from montreal_forced_aligner.alignment.adapting import AdaptingAligner
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\alignment\adapting.py", line 18, in
from montreal_forced_aligner.alignment.pretrained import PretrainedAligner
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\alignment\pretrained.py", line 50, in
from montreal_forced_aligner.transcription.transcriber import TranscriberMixin
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\transcription_init_.py", line 2, in
from montreal_forced_aligner.transcription.transcriber import Transcriber
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\transcription\transcriber.py", line 36, in
from montreal_forced_aligner.alignment.base import CorpusAligner
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\alignment\base.py", line 32, in
from montreal_forced_aligner.alignment.mixins import AlignMixin
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\alignment\mixins.py", line 23, in
from montreal_forced_aligner.dictionary.mixins import DictionaryMixin
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\dictionary_init_.py", line 8, in
from montreal_forced_aligner.dictionary.multispeaker import (
...<2 lines>...
)
File "C:\ASU\miniconda3\envs\aligner\Lib\site-packages\montreal_forced_aligner\dictionary\multispeaker.py", line 19, in
from kalpy.fstext.lexicon import G2PCompiler, LexiconCompiler
ImportError: cannot import name 'G2PCompiler' from 'kalpy.fstext.lexicon' (C:\ASU\miniconda3\envs\aligner\Lib\site-packages\kalpy\fstext\lexicon.py)
ERROR conda.cli.main_run:execute(142): conda run mfa model download dictionary english_us_arpa failed. (See above for error)

Proposed Solution

TODO

Notes

I'm trying not to work through it myself, to emulate a researcher who can't run CLI stuff.

[BeckettFrey]

I think this is a problem on the MFA setup side (a version mismatch between montreal-forced-aligner and kalpy), and the feedback here should be clearer and actionable rather than a raw traceback. Rather than putting too much effort into patching this specific case, I'm planning to bundle MFA into the app so the versions are locked down (Michaels idea), that should prevent this class of issue entirely. Could you share your installed versions for more context?

I think the steps for doing so on Windows are:

1. Open Anaconda Prompt from the Start menu.
2. Run: conda list -n aligner "montreal-forced-aligner|kalpy|kaldi"
3. Paste the output here.

[nrgslp]

[nrgslp]

what versions are you running? I can pin to your versions

[BeckettFrey]

We tracked down the root cause, and it's fixed upstream as of June 25. Here's what happened:

• kalpy 0.10.0 (published June 22) removed an API (G2PCompiler) that all released MFA versions still import, in preparation for the not-yet-released MFA 3.4.
• The MFA conda package at the time didn't cap its kalpy dependency (kalpy >=0.9), so any aligner env created between June 22 and June 25 got the incompatible pair — which is exactly what your screenshot shows (montreal-forced-aligner 3.3.9 pyhd8ed1ab_1 + kalpy 0.10.0). Every mfa command in that env crashes at import, which VoxKit surfaces as the dictionary-download error.
• conda-forge fixed the packaging on June 25 (build pyhd8ed1ab_2, which pins kalpy 0.9.*). I've verified a fresh install now resolves correctly and works.

We filed the details upstream: MontrealCorpusTools/Montreal-Forced-Aligner#959.

To fix your env, open Anaconda Prompt and either repair in place:

conda install -n aligner -c conda-forge "kalpy=0.9"

or delete and recreate it (a fresh solve now picks the fixed build):

conda remove -n aligner --all
conda create -n aligner -c conda-forge montreal-forced-aligner

Then confirm with conda run -n aligner mfa version — if that prints a version instead of a traceback, VoxKit will work.

Longer term this doesn't change the plan to bundle MFA with locked versions — your experience is a perfect example of the class of breakage bundling eliminates (you did nothing wrong here; the timing of your install was just unlucky).