`manim` Fails to Render Video in Command Line

[zhdbk3]

Description of bug / unexpected behavior

When executing manim in the command line, the video fails to render despite the process completing without errors.

Expected behavior

The video should render and preview successfully.

How to reproduce the issue

Code for reproducing the problem

# main.py
from manim import *


class DefaultTemplate(Scene):
    def construct(self):
        circle = Circle()  # create a circle
        circle.set_fill(PINK, opacity=0.5)  # set color and transparency

        square = Square()  # create a square
        square.flip(RIGHT)  # flip horizontally
        square.rotate(-3 * TAU / 8)  # rotate a certain amount

        self.play(Create(square))  # animate the creation of the square
        self.play(Transform(square, circle))  # interpolate the square into the circle
        self.play(FadeOut(square))  # fade out animation

manim main.py

Additional media files

Images/GIFs

Logs

Terminal output

$ manim main.py -v DEBUG
Manim Community v0.19.0

[08/02/25 21:12:28] DEBUG    Hashing ...                                                                                                                                  hashing.py:352
                    DEBUG    Hashing done in 0.002615 s.                                                                                                                  hashing.py:364
                    DEBUG    Hash generated :  3161293378_2169219173_223132457                                                                                            hashing.py:367
                    DEBUG    List of the first few animation hashes of the scene: ['3161293378_2169219173_223132457']                                               cairo_renderer.py:98
                    DEBUG    Hashing ...                                                                                                                                  hashing.py:352
                    DEBUG    Hashing done in 0.003385 s.                                                                                                                  hashing.py:364
                    DEBUG    Hash generated :  4088896323_2176658000_557880437                                                                                            hashing.py:367
                    DEBUG    List of the first few animation hashes of the scene: ['3161293378_2169219173_223132457', '4088896323_2176658000_557880437']            cairo_renderer.py:98
                    DEBUG    Hashing ...                                                                                                                                  hashing.py:352
                    DEBUG    Hashing done in 0.002369 s.                                                                                                                  hashing.py:364
                    DEBUG    Hash generated :  4088896323_2956010123_557880437                                                                                            hashing.py:367
                    DEBUG    List of the first few animation hashes of the scene: ['3161293378_2169219173_223132457', '4088896323_2176658000_557880437',            cairo_renderer.py:98
                             '4088896323_2956010123_557880437']                                                                                                                         
                    INFO     Rendered DefaultTemplate                                                                                                                       scene.py:255
                             Played 3 animations

System specifications

System Details

• OS (with version, e.g., Windows 10 v2004 or macOS 10.15 (Catalina)): Windows 11 24H2 26100.4652
• RAM: 32 GB
• Python version (python/py/python3 --version): Python 3.12.11
• Installed modules (provide output from pip list):

$ uv pip list
Using Python 3.12.11 environment at: D:\PycharmProjects\ManimVideos\.venv
Package           Version
----------------- -----------
av                13.1.0
beautifulsoup4    4.13.4
click             8.2.2
cloup             3.0.7
colorama          0.4.6
decorator         5.2.1
glcontext         3.0.0
isosurfaces       0.1.2
manim             0.19.0
manimpango        0.6.0
mapbox-earcut     1.0.3
markdown-it-py    3.0.0
mdurl             0.1.2
moderngl          5.12.0
moderngl-window   3.1.1
networkx          3.5
numpy             2.3.2
pillow            11.3.0
pycairo           1.28.0
pydub             0.25.1
pyglet            2.1.6
pyglm             2.8.2
pygments          2.19.2
rich              14.1.0
scipy             1.16.1
screeninfo        0.8.1
skia-pathops      0.8.0.post2
soupsieve         2.7
srt               3.5.3
svgelements       1.9.6
tqdm              4.67.1
typing-extensions 4.14.1
watchdog          6.0.0

LaTeX details

• LaTeX distribution (e.g. TeX Live 2020): MiKTeX 25.4
• Installed LaTeX packages:

Additional comments

• ✅ manim checkhealth successfully renders and previews CheckHealthDemo.
• ✅ Directly running main.py with DefaultTemplate().render(preview=True) works correctly.
• ❌ Only command-line invocation fails (manim main.py).

[uwezi]

did you try to use the command line switches for quality and preview?

manim -pql main.py your_scene_name

[zhdbk3]

did you try to use the command line switches for quality and preview?

manim -pql main.py your_scene_name

$ manim -pql main.py DefaultTemplate -v DEBUG
Manim Community v0.19.0

[08/02/25 21:46:14] DEBUG    Hashing ...                                                                                                                                  hashing.py:352
                    DEBUG    Hashing done in 0.002694 s.                                                                                                                  hashing.py:364
                    DEBUG    Hash generated :  1578262199_2169219173_223132457                                                                                            hashing.py:367
                    DEBUG    List of the first few animation hashes of the scene: ['1578262199_2169219173_223132457']                                               cairo_renderer.py:98
                    DEBUG    Hashing ...                                                                                                                                  hashing.py:352
                    DEBUG    Hashing done in 0.003481 s.                                                                                                                  hashing.py:364
                    DEBUG    Hash generated :  1613263639_2176658000_557880437                                                                                            hashing.py:367
                    DEBUG    List of the first few animation hashes of the scene: ['1578262199_2169219173_223132457', '1613263639_2176658000_557880437']            cairo_renderer.py:98
                    DEBUG    Hashing ...                                                                                                                                  hashing.py:352
                    DEBUG    Hashing done in 0.002452 s.                                                                                                                  hashing.py:364
                    DEBUG    Hash generated :  1613263639_2956010123_557880437                                                                                            hashing.py:367
                    DEBUG    List of the first few animation hashes of the scene: ['1578262199_2169219173_223132457', '1613263639_2176658000_557880437',            cairo_renderer.py:98
                             '1613263639_2956010123_557880437']                                                                                                                         
                    INFO     Rendered DefaultTemplate                                                                                                                       scene.py:255
                             Played 3 animations

There is no video file and nothing different.

[uwezi]

• where did you look for the video file?
• please also try
  manim -pql --disable_caching main.py DefaultTemplate
  in case something is wrong with the previously rendered and cached parts...

[zhdbk3]

• where did you look for the video file?
• please also try
  manim -pql --disable_caching main.py DefaultTemplate
  in case something is wrong with the previously rendered and cached parts...

• 

• $ manim -pql --disable_caching main.py DefaultTemplate -v DEBUG
  Manim Community v0.19.0
  
  [08/03/25 09:58:18] INFO     Caching disabled.                                                                                                                      cairo_renderer.py:79
                      DEBUG    List of the first few animation hashes of the scene: ['uncached_00000']                                                                cairo_renderer.py:98
                      INFO     Caching disabled.                                                                                                                      cairo_renderer.py:79
                      DEBUG    List of the first few animation hashes of the scene: ['uncached_00000', 'uncached_00001']                                              cairo_renderer.py:98
                      INFO     Caching disabled.                                                                                                                      cairo_renderer.py:79
                      DEBUG    List of the first few animation hashes of the scene: ['uncached_00000', 'uncached_00001', 'uncached_00002']                            cairo_renderer.py:98
                      INFO     Rendered DefaultTemplate                                                                                                                       scene.py:255
                               Played 3 animations
  

  It's of no use.

[zhdbk3]

I tried explicitly specifying the parameter --write_to_movie, and it finally successfully generated and previewed the video!

I noticed that both the FAQ and issue #4225 mention that this --write_to_movie parameter must be added when using the OpenGL renderer. However, I am not using OpenGL at all—I'm using Cairo.

Is this a bug with the Cairo renderer, or is the documentation inaccurate about this?

[behackl]

The cairo renderer writes files by default. Given that manim checkhealth passes and results in a video, manim itself is working. It appears manim is picking up some additional config settings somewhere -- is there a manim.cfg in the directory you are currently using? It might have been created automatically in case you used the manim CLI to create the project.

[zhdbk3]

The cairo renderer writes files by default. Given that manim checkhealth passes and results in a video, manim itself is working. It appears manim is picking up some additional config settings somewhere -- is there a manim.cfg in the directory you are currently using? It might have been created automatically in case you used the manim CLI to create the project.

Whether I keep or delete manim.cfg, it does not write files. Additionally, the manim.cfg file contains no configuration related to write_to_movie.

[behackl]

Can you please provide the full output of uv run manim cfg show?

Also, please share your manim.cfg, and check that you don't also have a user-wide configuration file (under Windows, manim looks at Roaming\Manim\manim.cfg in your user %appdata% directory.

[zhdbk3]

Can you please provide the full output of uv run manim cfg show?

Also, please share your manim.cfg, and check that you don't also have a user-wide configuration file (under Windows, manim looks at Roaming\Manim\manim.cfg in your user %appdata% directory.

$ uv run manim cfg show
Manim Community v0.19.0

DEFAULT


CLI
notify_outdated_version : True
write_to_movie : True
format : mp4
save_last_frame : False
write_all : False
save_pngs : False
zero_pad : 4
save_as_gif : False
save_sections : False
preview : False
show_in_file_browser : False
verbosity : INFO
progress_bar : display
output_file :
log_to_file : False
background_color : BLACK
background_opacity : 1
from_animation_number : 0
upto_animation_number : -1
media_dir : ./media
log_dir : {media_dir}/logs
assets_dir : ./
video_dir : {media_dir}/videos/{module_name}/{quality}
sections_dir : {video_dir}/sections
images_dir : {media_dir}/images/{module_name}
tex_dir : {media_dir}/Tex
text_dir : {media_dir}/texts
partial_movie_dir : {video_dir}/partial_movie_files/{scene_name}
renderer : cairo
enable_gui : False
gui_location : 0,0
fullscreen : False
window_position : UR
window_size : default
window_monitor : 0
force_window : False
use_projection_fill_shaders : False
use_projection_stroke_shaders : False
movie_file_extension : .mp4
frame_rate : 60
pixel_height : 1080
pixel_width : 1920
max_files_cached : 100
flush_cache : False
disable_caching : False
disable_caching_warning : False
enable_wireframe : False
dry_run : False
tex_template :
plugins :


CLI_CTX
align_option_groups : True
align_sections : True
show_constraints : True
indent_increment : 2
width : 80
col1_max_width : 30
col2_min_width : 35
col_spacing : 2
row_sep :
theme :
command_help :
invoked_command :
heading :
constraint :
section_help :
col1 :
col2 :
epilog :


custom_folders
media_dir : videos
video_dir : {media_dir}
sections_dir : {media_dir}
images_dir : {media_dir}
text_dir : {media_dir}/temp_files
tex_dir : {media_dir}/temp_files
log_dir : {media_dir}/temp_files
partial_movie_dir : {media_dir}/partial_movie_files/{scene_name}


logger
logging_keyword : bold yellow
logging_level_notset : dim
logging_level_debug : green
logging_level_info : green
logging_level_warning : red
logging_level_error : red bold
logging_level_critical : red bold reverse
log_level :
log_time : cyan dim
log_message :
log_path : dim
log_width : -1
log_height : -1
log_timestamps : True
repr_number : green


ffmpeg
loglevel : ERROR


jupyter
media_embed : False
media_width : 60%

This is my manim.cfg:

[CLI]
frame_rate = 60
pixel_height = 1080
pixel_width = 1920
background_color = BLACK
background_opacity = 1
scene_names = DefaultTemplate

I don't have a user-wide configuration file.

[behackl]

This is very odd, I've never seen this. The printed configuration shows that write_to_movie is set to True.

We'll have to investigate a bit closer. Can you ...

1. ... make sure you render in the correct python environment, i.e., by running uv run manim main.py,
2. ... insert print(f"write_to_movie setting: {config.write_to_movie}") below your from manim import *, and also as the first line in the construct method, then render again and share the output?

[zhdbk3]

This is very odd, I've never seen this. The printed configuration shows that write_to_movie is set to True.

We'll have to investigate a bit closer. Can you ...

1. ... make sure you render in the correct python environment, i.e., by running uv run manim main.py,
2. ... insert print(f"write_to_movie setting: {config.write_to_movie}") below your from manim import *, and also as the first line in the construct method, then render again and share the output?

False???

$ uv run manim main.py
Manim Community v0.19.0

write_to_movie setting: False
[08/03/25 16:46:17] INFO     Rendered DefaultTemplate                                                                                                                       scene.py:255
                             Played 3 animations

But when I add DefaultTemplate().render() and directly run main.py, it says write_to_movie setting: True.

[behackl]

Something messes with your settings. Unfortunately I can't say where this is coming from, and I also can't reproduce it on my machine. If you know your way around a debugger, you could theoretically set a break point at

manim/manim/_config/utils.py

Line 942 in 9c9ebf4

self._set_boolean("write_to_movie", value)

and check when exactly the setting is modified. Given that your global config seems to be fine though, I don't really see anything except for a "hidden" user-level config file that would cause this.

As a bandaid, you can always just add write_to_movie = True in your project manim.cfg, this should always have the highest priority and override any other settings that you might get from elsewhere.

Feel free to keep commenting, I'm closing this as not reproducible though.