Roboflow Custom Weights Upload

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Custom Weights Upload

Register weights from a model trained outside Roboflow (a laptop, a training server, Colab) so Roboflow can convert, host, and serve it.

Where the upload runs

Packaging reads the checkpoint from disk, so the upload always runs on the machine that has the weights — client-side, with the Python SDK flow below.

The models_upload_custom_weights MCP tool is a guide, not an uploader: calling it returns this recipe and echoes back the arguments you passed (its upload_mode field says whether they describe a versioned or a workspace upload, or undetermined when they pin down neither). It never packages or uploads anything, because the MCP server cannot read the user's filesystem.

Client-side upload with the Python SDK

Run this on the machine that has the weights, ideally in the same Python environment used for training (it already has torch and the matching ultralytics).

1. Install the SDK: both roboflow>=1.3.13 and rfdetr require Python >= 3.10; check python3 --version first (macOS ships 3.9). If it is too old, create a venv: uv venv --python 3.12 && source .venv/bin/activate. Then pip install "roboflow>=1.3.13".

2. Handle the API key safely: never ask the user to paste a private API key into chat, and never scan dotfiles, shell profiles, or config files hunting for one — permission systems rightly block that. If ROBOFLOW_API_KEY is already set in the environment (test -n "$ROBOFLOW_API_KEY") or the working project has a .env that defines it, use it. Otherwise mint a scoped key with the MCP api_keys_create tool — it returns the secret once (api_keys_roll is the only other tool that does; api_keys_list / api_keys_get return masked metadata) — and write it yourself to a .gitignore'd .env as ROBOFLOW_API_KEY. Writing .env does not populate os.environ: load it before running. For a .env you just wrote yourself, set -a; source .env; set +a is fine. For a pre-existing .env, never source it — sourcing executes any shell in the file and exports every other secret it holds into the process. Read only the one key instead, e.g. with python-dotenv (pip install python-dotenv) in the script:

   import os
   from dotenv import dotenv_values
   
   os.environ["ROBOFLOW_API_KEY"] = dotenv_values(".env")["ROBOFLOW_API_KEY"]
   

   Scope the key for the whole deploy flow, not minimally: the SDK's rf.workspace() reads the workspace and its project list before deploying, so project:read plus model:deploy alone fails with missing permissions. Include workspace:read, project:read, model:deploy, and for a versioned deploy also version:read and version:update. Getting the scopes right at mint time is what protects the upload: the preflight below only confirms the key and the workspace read, not the deploy scope.

   If the api_keys_create call is denied (permission systems may flag credential creation during an upload task) or unavailable, do not work around the denial. Ask the user to choose: (a) explicitly authorize minting a temporary scoped key, which you revoke with api_keys_revoke after the upload; (b) set ROBOFLOW_API_KEY themselves in their shell or a .env; or (c) point you at an existing .env that already defines it.

3. Confirm the destination and the name with the user: registering a model is not easily undone. Never infer the target project or version from the checkpoint's class count or filename — ask. The same goes for model_name on a workspace upload: ask the user what the model should be called; do not invent a name.

Preflight before packaging

Packaging plus a 100 MB+ upload is slow; run the cheap checks first and report every gap at once instead of failing one step at a time:

1. Python is >= 3.10 (python3 --version).

2. Required imports load: torch for YOLO, RF-DETR, and YOLO-NAS; ultralytics for YOLO v8/v10/v11/v12/26; rfdetr>=1.8.0 for raw PyTorch-Lightning RF-DETR checkpoints.

3. The key is valid and covers the workspace read — one cheap call that exercises the same workspace/project-list read deploy_model starts with:

   import os
   from roboflow import Roboflow
   
   Roboflow(api_key=os.environ["ROBOFLOW_API_KEY"]).workspace()
   

   Be honest about the limit of this check: it does not exercise model:deploy, which the platform only tests at models/prepareUpload, after packaging. That is why step 2 mints the key with the full scope set up front — the preflight catches a bad or under-read key, not a missing deploy scope on an existing key.

Only package and upload after all three pass.

Workspace model upload (no dataset version required):

import os
from roboflow import Roboflow

rf = Roboflow(api_key=os.environ["ROBOFLOW_API_KEY"])
workspace = rf.workspace("WORKSPACE_SLUG")
workspace.deploy_model(
    model_type="rfdetr-base",
    model_path="/path/to/training/output",
    project_ids=["PROJECT_SLUG"],
    model_name="MODEL_NAME",
    filename="checkpoint_best_total.pth",  # relative to model_path
)

Versioned deploy (attach weights to an existing dataset version):

import os
from roboflow import Roboflow

rf = Roboflow(api_key=os.environ["ROBOFLOW_API_KEY"])
version = rf.workspace("WORKSPACE_SLUG").project("PROJECT_SLUG").version(3)
version.deploy(
    model_type="yolov8n",
    model_path="/path/to/runs/detect/train",
    filename="weights/best.pt",
)

model_type must name the real architecture (yolov8n, yolov11s, rfdetr-base, rfdetr-seg-medium, yolonas, a supported PaliGemma or Florence-2 type). For YOLO families the SDK infers a missing size suffix from the weights; RF-DETR accepts no bare rfdetr — pass the exact variant, which the SDK cross-checks against the checkpoint.

On a size/variant or dependency mismatch, deploy_model / version.deploy print the error and then interactively prompt "Would you like to continue anyway? y/n" — in a headless run the prompt surfaces as an EOFError right after the printed error. Recover by error type:

• Size/variant mismatch: when the error names the type that fits, fix model_type to it and rerun; when it says the size could not be inferred, pass an explicit size.
• Dependency mismatch: the error names a pip pin, not a model type (yolov8 recommends ultralytics==8.0.196, so most current training environments hit this prompt). Install the named version, or — only with the user's explicit confirmation — answer y (headless: printf 'y\n' | python upload.py) to continue with the installed version.

Never force past either prompt without the user explicitly confirming the override is intentional.

Per-family requirements

• YOLO v8/v10/v11/v12/YOLO26: needs torch and ultralytics importable (yolov8 recommends ultralytics==8.0.196; see the dependency-mismatch note above). Legacy YOLO v5/v7/v9: needs torch plus an opt.yaml in model_path with imgsz (or img_size) and batch_size; ultralytics is not used. There is no yolov6 support.
• RF-DETR: needs torch to read the checkpoint. If a class_names.txt (one class per line) sits in model_path it is used; otherwise class names come from the checkpoint's args. Raw PyTorch-Lightning checkpoints additionally need rfdetr>=1.8.0 installed (the SDK's error names the exact minimum if yours is older). An explicit filename that does not exist is a hard error; the default weights/best.pt falls back to the first top-level .pt/.pth file, with a warning.
• YOLO-NAS: model_type="yolonas" plus an opt.yaml in model_path with imgsz, batch_size, and architecture.
• PaliGemma / Florence-2: model_path is the Hugging Face save directory (config, tokenizer, and weights files); no torch needed.

Verify the upload

Conversion runs server-side after the upload and usually takes a few minutes. Check it with the MCP models_list / models_get tools or at app.roboflow.com/WORKSPACE/PROJECT/models, then run a test inference on a sample image to confirm classes and predictions look right.