No module named 'groundingdino' or 'segment_anything' in ComfyUI

If ComfyUI logs ModuleNotFoundError: No module named 'groundingdino' or ModuleNotFoundError: No module named 'segment_anything', a segmentation custom node failed before it could register its ComfyUI nodes.

These errors often appear in SAM, GroundingDINO, masking, background removal, and object segmentation workflows. They are not ComfyUI core packages. They usually belong to a custom node such as comfyui_segment_anything or another segmentation pack that imports SAM or GroundingDINO during startup.

In the full Wonderful Launcher telemetry export ending June 29, 2026, groundingdino appeared across 20 affected installs, including 6 affected installs in the last 30 days. segment_anything appeared across 11 affected installs, including 4 affected installs in the last 30 days. Treat them as one segmentation repair chain unless the startup log names a different plugin.

.\python_embeded\python.exe -s -m pip install groundingdino-py
.\python_embeded\python.exe -s -m pip install git+https://github.com/facebookresearch/segment-anything.git
.\python_embeded\python.exe -s ComfyUI\main.py --windows-standalone-build

What the error looks like

GroundingDINO import failure:

IMPORT FAILED: comfyui_segment_anything
Traceback (most recent call last):
  File "...\custom_nodes\comfyui_segment_anything\__init__.py", line 1, in <module>
    import groundingdino
ModuleNotFoundError: No module named 'groundingdino'

SAM import failure:

IMPORT FAILED: ComfyUI-SAM
Traceback (most recent call last):
  File "...\custom_nodes\ComfyUI-SAM\__init__.py", line 5, in <module>
    from segment_anything import sam_model_registry, SamPredictor
ModuleNotFoundError: No module named 'segment_anything'

Common custom nodes that can trigger this class of error include comfyui_segment_anything, ComfyUI-SAM, ComfyUI-Impact-Pack features, background removal nodes, and other segmentation-related packs.

SAM package, SAM model, or GroundingDINO?

Segmentation workflows can fail at several layers:

Do not install every segmentation package at once. Fix the first missing import, restart, and then follow the next visible error.

Why it happens

• The custom node was cloned but its dependencies were not installed
• SAM and GroundingDINO are plugin-specific dependencies, not ComfyUI core dependencies
• A previous environment rebuild or update removed it
• The package was installed in a different Python environment than the one ComfyUI uses
• The Python package is fixed, but required model or config files are still missing

Quick diagnosis

Safe manual fix

Step 1: Install only the missing import

If the error says groundingdino:

For Windows portable:

.\python_embeded\python.exe -s -m pip install groundingdino-py

For a manual venv:

python -m pip install groundingdino-py

If the error says segment_anything, use the official Segment Anything source:

.\python_embeded\python.exe -s -m pip install git+https://github.com/facebookresearch/segment-anything.git

For a manual venv:

python -m pip install git+https://github.com/facebookresearch/segment-anything.git

There is also a segment-anything package on PyPI, but Meta's official repository documents the GitHub install path. Prefer the plugin README when it gives a specific command.

Step 2: Download the model files required by the plugin

The Python packages provide code. Segmentation workflows also need model files.

For comfyui_segment_anything, the README expects GroundingDINO files under:

ComfyUI\models\grounding-dino\

and SAM checkpoints under:

ComfyUI\models\sams\

For SAM, common checkpoint choices include:

• SAM ViT-H (default, largest): sam_vit_h_4b8939.pth (~2.4 GB)
• SAM ViT-L (large): sam_vit_l_0b3195.pth (~1.2 GB)
• SAM ViT-B (base, smallest): sam_vit_b_01ec64.pth (~375 MB)

The exact folder depends on your custom node's configuration. Check the node's README for the expected model location.

Step 3: Check for additional dependencies

Some SAM-based nodes also require:

.\python_embeded\python.exe -s -m pip install pycocotools

Only install extra packages if the startup log shows additional import errors after fixing the first missing package.

Step 4: Restart and verify

.\python_embeded\python.exe -s ComfyUI\main.py --windows-standalone-build

The SAM or GroundingDINO-related nodes should now appear in the node list. If the plugin imports cleanly but execution fails at GroundingDinoModelLoader or SAMModelLoader, switch from Python-package repair to model-file placement.

When not to run pip install blindly

• Segment Anything depends on torch and torchvision. If your environment already has CUDA-enabled PyTorch, avoid package commands that replace Torch or TorchVision unexpectedly
• GroundingDINO may compile or install native pieces depending on the package path, CUDA, Python, and platform. Stop if the error changes into a compiler, CUDA, or wheel failure
• Some custom nodes bundle their own SAM code instead of using the pip package. Check whether the node README says to install from pip or from the node's own requirements
• Do not install segment-anything-py or other similarly named packages — they may be forks with different APIs
• Do not keep reinstalling Python packages when the next error is a missing .pth, config file, or Hugging Face model directory

How Wonderful Launcher can help

Wonderful Launcher can help separate the repair stages: plugin import, missing Python package, model file placement, and queue-time runtime errors. That matters for SAM/GroundingDINO workflows because fixing the Python import often reveals a second model-file issue.

Download Wonderful Launcher — it's free and can recover your environment without reinstalling.

Related errors

• ComfyUI Plugin Import Failed
• Fix No module named errors in ComfyUI
• ComfyUI ONNX Missing
• ComfyUI Dependency Conflicts
• ComfyUI Startup Failed
• Plugin Missing Module Warning: When It Is Safe to Ignore

Source References

• comfyui_segment_anything GitHub repository
• Meta Segment Anything GitHub repository
• groundingdino-py on PyPI
• ComfyUI GitHub