Claude AI desktop no longer connecting to Blender MCP server?

[sudojorno1]

yesterday I lost the ability to connect to my Blender MCP server.

[virusvjvisuals]

same issue here...can t connect with blender s mcp addon anymore

[ahujasid]

Looking into this

[ahujasid]

@sudojorno1 @virusvjvisuals is it working now?

[coffeenmusic]

Doesn't Anthropic now require installation via a Desktop Extension (.dxt) file?

[whitescent]

I'm also experiencing this issue. The Blender MCP in Claude Desktop seems to be stuck in a running state, but it works fine on cursor.

[LarissaSmith]

I'm having issues with a new installation of blender-mcp, which appear to be a result of this: modelcontextprotocol/python-sdk#1198. Someone merged a breaking change in a patch release, which makes me think it would be wise if blender-mcp was locked to a specific version of mcp. (I've been trying to do it in my own downloaded version, but for some reason after reinstalling the add-on with the change, it's still downloading the old version.)

[LarissaSmith]

@ahujasid I can't be certain that this is the issue that affected the user that opened the thread, but I think it would affect any users who downloaded or installed blender-mcp in the last week. So i thought it would be good to alert the blender-mcp devs.

[virusvjvisuals]

@sudojorno1 @virusvjvisuals is it working now?

from blender side , it seemed it had no issues but claude desktop failed to connect to the blender addon server, i seemed that claude desktop hadn't anymore the blender mcp service available and activated to be used into claude desktop anymore
First i reinstalled uvx and checked the install
pip install uvx -y
and then :
uvx version
and
uv version

and checked claude to get analysis on the issue , seemed that the blender mcp had to be add as a new custom mcp in the parameters
To activate the Blender MCP tool:

In Claude: Go to Settings → Features → MCP Tools
Add a new connection:

Type: MCP Server
URL: http://localhost:9876
Name: Blender MCP

Verify Blender is ready:

MCP Server addon installed and enabled
Server running on port 9876
No firewall blocking

Test the connection in settings

go to file > develloper > reload the mcp config

close claude completely
in blender : i uninstalled the blendermcp and reinstallled it , saved preferences, and closed blender

after that , reopened blender,
launched the blendermcp addon server on default port
launched claude
checked into developper settings the availability of blender mcp

finally i did a test prompting for the actual blender scene analysis into claude
was working finally (but struggled almost a complete night to recover my blender mcp service working again;... kinda painful issue and clearly no info from anthropic about this issue ...

[LeeDog2]

this happened on the newest updated cherrystudio too. i suspect that this application is a plagiarism for claude desktop, which sharing the same kernel.

[ahujasid]

It seems to be working fine when I test locally - could you paste an error description?

[ahujasid]

A suggestion by the FastMCP team:

For uvx users, a temporary fix for this is to have mcp==1.12.2 in a requirements.txt file and add --with-requirements=requirements.txt as the first arugment to uvx.

{
    "mcpServers": {
        "blender": {
            "command": "uvx",
            "args": [
                "blender-mcp"
            ]
             "env": {
                    "UV_CONSTRAINT": "requirements.txt"
                  }
        }
    }
}