Having connection issues even though both processes are running

[soederpop]

I'm on a mac using the latest version of claude desktop

here is the blender logs

❯ /Applications/Blender.app/Contents/MacOS/Blender

openai already installed
BlenderMCP addon registered
BlenderMCP server started on localhost:9876
Connected to client: ('127.0.0.1', 54162)

here are the logs from running uvx blender-mcp

 uvx blender-mcp                                 
2025-03-11 21:46:32,495 - BlenderMCPServer - INFO - BlenderMCP server starting up
2025-03-11 21:46:32,496 - BlenderMCPServer - INFO - Connected to Blender at localhost:9876
2025-03-11 21:46:32,496 - BlenderMCPServer - INFO - Created new persistent connection to Blender
2025-03-11 21:46:32,496 - BlenderMCPServer - INFO - Successfully connected to Blender on startup

Here is what I see in claude

Previously before I was running that blender-mcp command I would get errors opening up claude and it wouldnt see the tools, those went away and the desktop app sees 9 available tools

The communication still fails. Let me know how I can help debug

[soederpop]

Here are the blender mcp logs

2025-03-11 22:18:53,616 - mcp.server.lowlevel.server - INFO - Processing request of type CallToolRequest
2025-03-11 22:18:53,617 - BlenderMCPServer - INFO - Sending command: get_scene_info with params: None
2025-03-11 22:18:53,617 - BlenderMCPServer - INFO - Command sent, waiting for response...
2025-03-12T03:18:57.173Z [blender] [info] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":41}
2025-03-12T03:19:02.173Z [blender] [info] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":42}
2025-03-12T03:19:02.174Z [blender] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":41,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-12T03:19:02.175Z [blender] [info] Message from client: {"method":"prompts/list","params":{},"jsonrpc":"2.0","id":43}
2025-03-12T03:19:07.172Z [blender] [info] Message from client: {"method":"resources/list","params":{},"jsonrpc":"2.0","id":44}
2025-03-12T03:19:07.173Z [blender] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":42,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-12T03:19:07.174Z [blender] [info] Message from client: {"method":"prompts/list","params":{},"jsonrpc":"2.0","id":45}
2025-03-12T03:19:08.173Z [blender] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":43,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-11 22:19:08,619 - BlenderMCPServer - WARNING - Socket timeout during chunked receive
2025-03-11 22:19:08,619 - BlenderMCPServer - ERROR - Error communicating with Blender: No data received
2025-03-11 22:19:08,620 - BlenderMCPServer - ERROR - Error getting scene info from Blender: Communication error with Blender: No data received

There's a lot of noise from the claude desktop app checking for resources / prompts. Maybe your plugin can not log those unless a flag is set for your own sanity

[StreakingMan]

same problem

[ahujasid]

Hi, you don't need to run the uvx command in the terminal. Open Claude, go to Settings > Developer > Edit Config

And paste this in the file:

{
    "mcpServers": {
        "blender": {
            "command": "uvx",
            "args": [
                "blender-mcp"
            ]
        }
    }
}

Then, restart Claude, run the server on the addon. The server is finicky so you might need to restart it again by pressing Stop and Start. Let me know if that works.

[StreakingMan]

I have set everything... 😢

[ahujasid]

Is the uvx command running on terminal too? It shouldn't, try closing the terminal prompt, restarting Claude and Blender. Your setup looks fine otherwise. The terminal command might be occupying the same port as Claude, which is why it can't communicate.

[lfh1991]

Here are mcp-server-blender.log

2025-03-12T07:12:45.384Z [blender] [info] Initializing server...
2025-03-12T07:12:45.392Z [blender] [info] Server started and connected successfully
2025-03-12T07:12:45.393Z [blender] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
2025-03-12T07:12:46.374Z [blender] [info] Initializing server...
2025-03-12T07:12:46.381Z [blender] [info] Server started and connected successfully
2025-03-12T07:12:46.407Z [blender] [info] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
Downloading pydantic-core (1.7MiB)
Downloading pydantic-core (1.7MiB)
2025-03-12T07:13:45.395Z [blender] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-12T07:13:45.396Z [blender] [info] Client transport closed
2025-03-12T07:13:45.397Z [blender] [info] Server transport closed
2025-03-12T07:13:45.397Z [blender] [info] Client transport closed
2025-03-12T07:13:45.397Z [blender] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-03-12T07:13:45.397Z [blender] [error] Server disconnected. For troubleshooting guidance, please visit our debugging documentation {"context":"connection"}
2025-03-12T07:13:45.401Z [blender] [info] Server transport closed
2025-03-12T07:13:45.401Z [blender] [info] Client transport closed
2025-03-12T07:13:46.397Z [blender] [info] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-12T07:13:46.398Z [blender] [info] Client transport closed
2025-03-12T07:13:46.398Z [blender] [info] Server transport closed
2025-03-12T07:13:46.398Z [blender] [info] Client transport closed
2025-03-12T07:13:46.398Z [blender] [info] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-03-12T07:13:46.398Z [blender] [error] Server disconnected. For troubleshooting guidance, please visit our debugging documentation {"context":"connection"}
2025-03-12T07:13:46.402Z [blender] [info] Server transport closed
2025-03-12T07:13:46.402Z [blender] [info] Client transport closed

Here are mcp.log

2025-03-12T07:12:45.384Z [info] [blender] Initializing server...
2025-03-12T07:12:45.392Z [info] [blender] Server started and connected successfully
2025-03-12T07:12:45.393Z [info] [blender] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
2025-03-12T07:12:46.374Z [info] [blender] Initializing server...
2025-03-12T07:12:46.381Z [info] [blender] Server started and connected successfully
2025-03-12T07:12:46.407Z [info] [blender] Message from client: {"method":"initialize","params":{"protocolVersion":"2024-11-05","capabilities":{},"clientInfo":{"name":"claude-ai","version":"0.1.0"}},"jsonrpc":"2.0","id":0}
2025-03-12T07:13:45.395Z [info] [blender] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-12T07:13:45.396Z [info] [blender] Client transport closed
2025-03-12T07:13:45.397Z [info] [blender] Server transport closed
2025-03-12T07:13:45.397Z [info] [blender] Client transport closed
2025-03-12T07:13:45.397Z [info] [blender] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-03-12T07:13:45.397Z [error] [blender] Server disconnected. For troubleshooting guidance, please visit our debugging documentation
2025-03-12T07:13:45.401Z [info] [blender] Server transport closed
2025-03-12T07:13:45.401Z [info] [blender] Client transport closed
2025-03-12T07:13:46.397Z [info] [blender] Message from client: {"jsonrpc":"2.0","method":"notifications/cancelled","params":{"requestId":0,"reason":"Error: MCP error -32001: Request timed out"}}
2025-03-12T07:13:46.398Z [info] [blender] Client transport closed
2025-03-12T07:13:46.398Z [info] [blender] Server transport closed
2025-03-12T07:13:46.398Z [info] [blender] Client transport closed
2025-03-12T07:13:46.398Z [info] [blender] Server transport closed unexpectedly, this is likely due to the process exiting early. If you are developing this MCP server you can add output to stderr (i.e. console.error('...') in JavaScript, print('...', file=sys.stderr) in python) and it will appear in this log.
2025-03-12T07:13:46.399Z [error] [blender] Server disconnected. For troubleshooting guidance, please visit our debugging documentation
2025-03-12T07:13:46.402Z [info] [blender] Server transport closed
2025-03-12T07:13:46.402Z [info] [blender] Client transport closed

[kvick-games]

yeah. I had a lot of connection issues when I first started it. then for some reason it just started working. then it stopped working for a few more attempts and then it worked again? Seems like the connection is inconsistent for some reason

[LiamWu50]

Claude failed to connect to MCP blender

[ahujasid]

Claude failed to connect to MCP blender

@LiamWu50 if you are on Mac, you need to brew install uv, that should fix it

[ahujasid]

@lfh1991 your config looks correct. Here are some troubleshooting steps:

1. Ensure you have uv package manager installed
2. Ensure the Blender addon is installed and running the server
3. Ensure that uvx command isn't running in the terminal, only in Claude Desktop
4. Restart both Blender and Claude and try again

[aaaa-zhen]

@lfh1991 your config looks correct. Here are some troubleshooting steps:

1. Ensure you have uv package manager installed
2. Ensure the Blender addon is installed and running the server
3. Ensure that uvx command isn't running in the terminal, only in Claude Desktop
4. Restart both Blender and Claude and try again

here's mine...

[ahujasid]

@aaaa-zhen this issue is documented: #5

[lfh1991]

@lfh1991 your config looks correct. Here are some troubleshooting steps:

1. Ensure you have uv package manager installed
2. Ensure the Blender addon is installed and running the server
3. Ensure that uvx command isn't running in the terminal, only in Claude Desktop
4. Restart both Blender and Claude and try again

I restarted Blender and Claude and the hammer icon finally appeared, but when I sent Claude a modeling request, it responded like this:
I'll create an isometric scene in Blender with a dragon standing next to a pot of gold, using playful lighting and proper materials. Let's build this step by step!
First, let's get information about the current scene:View result from get_scene_info from blender (local){}Error getting scene info: Could not connect to Blender. Make sure the Blender addon is running.It seems we need to set up our scene from scratch. I'll create the main elements one by one:

First, let's create a plane to serve as our ground:
View result from create_object from blender (local){
name: Ground,
type: PLANE,
scale: [
5,
5,
1
]
}Error creating object: Could not connect to Blender. Make sure the Blender addon is running.I apologize for the error messages. It seems there might be an issue with the connection to Blender. Let me try using a more direct approach with the Blender Python API:View result from execute_blender_code from blender (local){
code: `
import bpy
import math
import random
from mathutils import Vector

Clear existing objects

bpy.ops.object.select_all(action='SELECT')
bpy.ops.object.delete()

Set up isometric camera

bpy.ops.object.camera_add(location=(10, -10, 10))
camera = bpy.context.active_object
camera.name = "IsometricCamera"
camera.rotation_euler = (math.radians(55), 0, math.radians(45))
camera.data.type = 'PERSP'
camera.data.lens = 40

Make this the active camera

bpy.context.scene.camera = camera

Create ground plane

bpy.ops.mesh.primitive_plane_add(size=10, location=(0, 0, 0))
ground = bpy.context.active_object
ground.name = "Ground"

Create a material for the ground

ground_mat = bpy.data.materials.new(name="GroundMaterial")
ground_mat.use_nodes = True
nodes = ground_mat.node_tree.nodes
nodes["Principled BSDF"].inputs["Base Color"].default_value = (0.15, 0.6, 0.3, 1.0)
nodes["Principled BSDF"].inputs["Roughness"].default_value = 0.8
ground.data.materials.append(ground_mat)

Create a pot of gold

bpy.ops.mesh.primitive_cylinder_add(radius=1, depth=1.5, location=(2, 0, 0.75))
pot = bpy.context.active_object
pot.name = "GoldPot"

Create a material for the pot

pot_mat = bpy.data.materials.new(name="PotMaterial")
pot_mat.use_nodes = True
nodes = pot_mat.node_tree.nodes
nodes["Principled BSDF"].inputs["Base Color"].default_value = (0.1, 0.1, 0.1, 1.0)
nodes["Principled BSDF"].inputs["Metallic"].default_value = 0.9
nodes["Principled BSDF"].inputs["Roughness"].default_value = 0.2
pot.data.materials.append(pot_mat)

Create gold coins (spheres)

for i in range(30):
x = 2 + random.uniform(-0.6, 0.6)
y = random.uniform(-0.6, 0.6)
z = 1.5 + random.uniform(0, 0.5)
bpy.ops.mesh.primitive_uv_sphere_add(radius=0.15, location=(x, y, z))
coin = bpy.context.active_object
coin.name = f"GoldCoin_{i}"

# Create a material for the gold coins
if i == 0:
    gold_mat = bpy.data.materials.new(name=\"GoldMaterial\")
    gold_mat.use_nodes = True
    nodes = gold_mat.node_tree.nodes
    nodes[\"Principled BSDF\"].inputs[\"Base Color\"].default_value = (1.0, 0.8, 0.0, 1.0)
    nodes[\"Principled BSDF\"].inputs[\"Metallic\"].default_value = 1.0
    nodes[\"Principled BSDF\"].inputs[\"Specular\"].default_value = 0.5
    nodes[\"Principled BSDF\"].inputs[\"Roughness\"].default_value = 0.1

coin.data.materials.append(gold_mat)

Create a stylized dragon

bpy.ops.mesh.primitive_cube_add(size=1, location=(-2, 1, 1))
dragon_body = bpy.context.active_object
dragon_body.name = "DragonBody"
dragon_body.scale = (2, 1, 1)

Create dragon head

bpy.ops.mesh.primitive_cone_add(radius1=0.6, radius2=0, depth=1.5, location=(-3.5, 1, 1.2))
dragon_head = bpy.context.active_object
dragon_head.name = "DragonHead"
dragon_head.rotation_euler = (0, math.radians(90), 0)

Create dragon tail

bpy.ops.mesh.primitive_cone_add(radius1=0.4, radius2=0, depth=2, location=(-0.5, 1, 1))
dragon_tail = bpy.context.active_object
dragon_tail.name = "DragonTail"
dragon_tail.rotation_euler = (0, math.radians(-90), 0)

Create dragon legs (4)

leg_positions = [(-1.5, 1.5, 0.2), (-1.5, 0.5, 0.2), (-2.5, 1.5, 0.2), (-2.5, 0.5, 0.2)]
for i, pos in enumerate(leg_positions):
bpy.ops.mesh.primitive_cylinder_add(radius=0.2, depth=0.8, location=pos)
leg = bpy.context.active_object
leg.name = f"DragonLeg_{i}"

Create dragon wings (2)

wing_positions = [(-2, 1.5, 1.5), (-2, 0.5, 1.5)]
for i, pos in enumerate(wing_positions):
bpy.ops.mesh.primitive_cone_add(radius1=0.8, radius2=0, depth=1.2, location=pos)
wing = bpy.context.active_object
wing.name = f"DragonWing_{i}"
wing.rotation_euler = (0, 0, math.radians(90 if i == 0 else -90))

Create dragon material

dragon_mat = bpy.data.materials.new(name="DragonMaterial")
dragon_mat.use_nodes = True
nodes = dragon_mat.node_tree.nodes
nodes["Principled BSDF"].inputs["Base Color"].default_value = (0.8, 0.1, 0.1, 1.0)
nodes["Principled BSDF"].inputs["Roughness"].default_value = 0.7

Apply material to all dragon parts

for obj in bpy.data.objects:
if "Dragon" in obj.name:
obj.data.materials.append(dragon_mat)

Add eyes to dragon

for i, x_offset in enumerate([0.2, -0.2]):
bpy.ops.mesh.primitive_uv_sphere_add(radius=0.1, location=(-4, 1 + x_offset, 1.2))
eye = bpy.context.active_object
eye.name = f"DragonEye_{i}"

# Create eye material
eye_mat = bpy.data.materials.new(name=f\"EyeMaterial_{i}\")
eye_mat.use_nodes = True
nodes = eye_mat.node_tree.nodes
nodes[\"Principled BSDF\"].inputs[\"Base Color\"].default_value = (1.0, 1.0, 0.0, 1.0)
nodes[\"Principled BSDF\"].inputs[\"Emission\"].default_value = (1.0, 1.0, 0.0, 1.0)
nodes[\"Principled BSDF\"].inputs[\"Emission Strength\"].default_value = 2.0
eye.data.materials.append(eye_mat)

Set up lighting for playful mood

Key light

bpy.ops.object.light_add(type='AREA', radius=1, location=(5, -5, 8))
key_light = bpy.context.active_object
key_light.name = "KeyLight"
key_light.data.energy = 300
key_light.data.color = (1.0, 0.9, 0.8)

Fill light

bpy.ops.object.light_add(type='AREA', radius=1, location=(-8, 2, 5))
fill_light = bpy.context.active_object
fill_light.name = "FillLight"
fill_light.data.energy = 150
fill_light.data.color = (0.8, 0.9, 1.0)

Rim light

bpy.ops.object.light_add(type='AREA', radius=1, location=(2, 8, 6))
rim_light = bpy.context.active_object
rim_light.name = "RimLight"
rim_light.data.energy = 200
rim_light.data.color = (1.0, 0.8, 0.6)

Set up rendering

bpy.context.scene.render.engine = 'CYCLES'
bpy.context.scene.cycles.samples = 128
bpy.context.scene.render.resolution_x = 1920
bpy.context.scene.render.resolution_y = 1920
bpy.context.scene.render.film_transparent = True

Add a subtle environment light

world = bpy.context.scene.world
world.use_nodes = True
bg = world.node_tree.nodes["Background"]
bg.inputs["Color"].default_value = (0.05, 0.05, 0.08, 1.0)
bg.inputs["Strength"].default_value = 1.0

Return a message

return "Created an isometric scene with a dragon next to a pot of gold, with playful lighting and materials."
}Error executing code: Could not connect to Blender. Make sure the Blender addon is running.I apologize for the continued connection issues. It seems there might be a problem with the Blender addon or connection. Let me try a simpler approach:View result from create_primitive from blender (local){type: CUBE`
}No result received from client-side tool execution.I apologize for the technical difficulties. It appears that we're encountering consistent connection issues with the Blender addon.
Here's what the scene would look like if we could create it:

Isometric View Setup:

An isometric camera positioned at an angle to give that classic isometric look
Clean background with subtle gradient

Dragon Model:

A stylized, cartoon-like dragon (not too scary)
Red/orange coloration with subtle scales
Yellow glowing eyes for a playful touch
Wings slightly spread to add visual interest
Posed looking curiously at the gold

Pot of Gold:

Black cauldron-style pot with metallic reflections
Filled with bright gold coins that have high metallic properties
Some coins spilling out onto the ground

Lighting Setup:

Main warm key light from the upper right (golden hue)
Blue-tinted fill light from the left
Subtle rim light to outline the dragon
Global illumination for soft shadows

Materials:

Dragon: Slightly matte red/orange material with subtle bump mapping for scales
Pot: Dark metallic material with slight reflection
Gold: High metallic, low roughness yellow-gold material with reflections
Ground: Simple green material with subtle texture

Rendering:

Cycles renderer for quality lighting and reflections
Depth of field focused on the scene
Subtle post-processing for color enhancement

This would create a Dribbble-worthy isometric scene with a playful mood and polished appearance.
Would you like me to try a different approach, or would you prefer instructions on how to create this scene manually in Blender?

[ahujasid]

@lfh1991 is the addon running? sometimes there are connection errors, you can try restarting it. If it connected once it should work

[LiamWu50]

Claude 无法连接到 MCP 搅拌机

如果您使用的是 Mac，则需要 brew install uv，这应该可以修复它

Thank you, it's working