FileNotFoundError: [Errno 2] No such file or directory:

[xboboji]

Hi, when I tried to convert my custom coco dataset to yolo format, I got the below error:

My script is shown below:

from ultralytics.data.converter import convert_coco
convert_coco(labels_dir={my annotation path}', save_dir='{output path}/labels', use_segments=False, use_keypoints=False, cls91to80=False)

I checked the error and fixed it by adding one line:

os.makedirs((fn / f).parent, exist_ok=True)

I wonder if it is a minor bug in this tool or something only happened specifically for my case?

Thanks!

[UltralyticsAssistant]

👋 Hello @xboboji, thank you for submitting a ultralytics/JSON2YOLO 🚀 Issue! This is an automated response—an Ultralytics engineer will also assist you soon.

To help us investigate your FileNotFoundError efficiently, could you please provide a minimum reproducible example (MRE)? This will help us determine if the issue is specific to your dataset or a more general bug. Please include:

1. A concise snippet or notebook that consistently triggers the error
2. Your environment details (OS, Python version, package versions)
3. The command or script you used (with any relevant paths)
4. The full error traceback or message
5. Any modifications you made to the code (such as your fix)

Please also make sure you’ve searched existing issues to avoid duplicates. Feel free to add any additional information in a comment below! 🛠️

Thank you for helping us improve JSON2YOLO!

[pderrenger]

Thanks for the detailed bug report and the fix! This appears to be a legitimate issue where subdirectories in the file path aren't being created before writing labels. Please first verify this still occurs with the latest ultralytics version (pip install -U ultralytics), and if so, consider submitting a pull request with your fix to help other users experiencing the same issue.

[glenn-jocher]

Thanks @xboboji. This is fixed on main now in commit ff25841, which creates parent label directories before writing files for image paths that include subdirectories. I verified the fix with a nested file_name smoke test. Please update from main or use the current ultralytics.data.converter.convert_coco() path for new workflows.