[BUG] Blender Connector Fails to Download/Run

Closing for now — this doesn't appear to be about Claude Code. Please open a new issue if this is still relevant.

the issue is still occurring on my pc.
windows 11, blender 5.1.2

same issue for me. this looks like it's about an "anti-virus / Ssl / uv " inconsistency. i have Norton, i disabled it but not solved. i tried to use windows ssl instead of anti-virus ssl. to do this open Powershell and enter this command:

[System.Environment]::SetEnvironmentVariable("UV_NATIVE_TLS","1","User")

check extensions folder if there exists any Blender folder, if there is, remove all. restart Claude desktop and try to install the extension.

i am having the same issue , cannot able to install the blender connector in claude , i also tried manually installing but still its not working , i have tried reinstalling several times too , eventually reinstalling the windows i thought some manual installation , can cause conflict, but it still giving that same issue, if anyone able to solve it , pls share the solution

I used Claude to help me figure out the issue and fix it. Here's a summary of the chat:

On Windows, the Blender MCP connector (Claude Desktop extension) fails to attach. There are two independent root causes, and fixing the first just exposes the second.

Environment: Windows 11, Claude Desktop (MSIX/Microsoft Store packaged build), uv 0.10.9, only Python on system is Microsoft Store Python 3.13.

Bug 1 — uv run re-syncs on every startup and the editable build fails

The manifest launches the server with uv run blender-mcp. uv run re-syncs the venv on every start, which triggers an editable install of the package. setuptools' egg_info step then fails:

× Failed to build `blender-mcp @ file:///C:/Users/...
╰─▶ Call to `setuptools.build_meta.build_editable` failed (exit code: 1)
    error: error in 'egg_base' option: '.' does not exist or is not a directory

The extension install path contains a space (Claude Extensions), which uv passes to setuptools URL-encoded as Claude%20Extensions. setuptools fails to resolve . against that URI during the editable build. This also makes the in-app Install/Reinstall button fail outright with the same error.

Bug 2 — venv built against Microsoft Store Python can't launch the console script

After forcing a non-editable install + --no-sync, the server still dies with:

.venv\Scripts\python.exe: can't open file '...\.venv\Scripts\blender-mcp.exe':
[Errno 2] No such file or directory

The file exists. The problem is the venv was created against Microsoft Store Python, which is itself an MSIX-sandboxed app. When the pip-generated blender-mcp.exe launcher tries to load itself through that interpreter, path resolution crosses the MSIX package boundary and Windows denies it. (Claude Desktop being MSIX-packaged too makes this worse.) On a machine where the only Python is the Store build, every venv uv auto-creates hits this.

Fix that worked

Rebuild the venv against a non-MSIX Python (uv's managed CPython) and stop uv run from re-syncing. In the extension folder
(%APPDATA%\Claude\Claude Extensions\ant.dir.gh.blender.blender-mcp):

uv python install 3.13                      # uv-managed, non-MSIX CPython
rm -rf .venv
uv venv --python 3.13 --managed-python
uv pip install .                            # non-editable

Then edit manifest.json to skip the per-launch resync:

"mcp_config": {
  "command": "uv",
  "args": ["run", "--no-sync", "blender-mcp"]   // added --no-sync
}

Fully quit Claude Desktop (system tray → Quit) and relaunch.

Suggested upstream fixes

• Don't rely on an editable install at runtime — ship a non-editable install, or make the entry point python -m blmcp so no console-script launcher is needed.
• Be robust to spaces in the install path (the Claude Extensions directory).
• Don't build the venv against Microsoft Store Python; prefer a managed/standalone interpreter.

This issue has been automatically locked since it was closed and has not had any activity for 7 days. If you're experiencing a similar issue, please file a new issue and reference this one if it's relevant.