[BUG]: MCP server crashes when deployed to Databricks app

[Ritaja]

Is there an existing issue for this?

• I have searched the existing issues

Current Behavior

I am trying to follow the tutorial in the readme and deploy MCP server. I am using windows PowerShell.

I am building and deploying app using the following commands:

$Env:BUNDLE_VAR_schema_full_name="retail.default" ; $Env:BUNDLE_VAR_genie_space_ids = '[\"<id>\"]' 
>   databricks bundle deploy

$Env:BUNDLE_VAR_schema_full_name="retail.default" ; $Env:BUNDLE_VAR_genie_space_ids = '[\"<id>\"]' 
>   databricks bundle run mcp-on-apps

The app deploys and crashes with error:

REDACTED_JWT: error parsing value for field "genie_space_ids" from source "EnvSettingsSource"

I checked the deployed app.yml (in Source:/Workspace/Users//.bundle/mcp-on-apps/dev/files/.build)contains:

command:
  - uvicorn
  - databricks.labs.mcp.servers.unity_catalog.app:app
env:
  - name: SCHEMA_FULL_NAME
    value: retail.default
  - name: GENIE_SPACE_IDS
    value: '[\"01f03b71f9d81af09c6ae3911a46cc34\"]'

Operating System

windows

[renardeinside]

hey @Ritaja ,
I think this is related to how you pass the environment variables - seems like the escaping sequence on Windows is different. Could you please try:

$Env:BUNDLE_VAR_schema_full_name="retail.default" ; $Env:BUNDLE_VAR_genie_space_ids = '["<id>"]' 
>   databricks bundle deploy

Without the \ characters?

[Ritaja]

Thanks @renardeinside this helped get past first hurdle; but the app still crashes. The logs do not say anything. The app state is "crashed"

The current app.yml is:

command:
  - uvicorn
  - databricks.labs.mcp.servers.unity_catalog.app:app
env:
  - name: SCHEMA_FULL_NAME
    value: retail.default
  - name: GENIE_SPACE_IDS
    value: '["id"]'

logs (head):

[2025-06-04 14:55:45] [Databricks] [INFO] [01f04153edd211b3aa0c040f27b80c9d] Deployment successful
[2025-06-04 14:55:45] [Databricks] [INFO] Deployment 01f04153edd211b3aa0c040f27b80c9d ended in 25.241993664s
[2025-06-04 14:55:43] [Databricks] [INFO] Starting app with command: [uvicorn databricks.labs.mcp.servers.unity_catalog.app:app]
[2025-06-04 14:55:43] [Databricks] [INFO] Requirements installed successfully.
▶
Successfully installed Mako-1.3.10 SQLAlchemy-2.0.41 aiohappyeyeballs-2.6.1 aiohttp-3.12.8 aiohttp-retry-2.9.1 aiosignal-1.3.2 alembic-1.16.1 databricks-ai-bridge-0.5.1 databricks-connect-16.1.5 databricks-labs-mcp-0.1.dev40+g2abfff6 databricks-opena...

I am probably doing something wrong, how can I debug this ?

[renardeinside]

Hey @Ritaja ,
could you please try the latest version in master branch? I've made several improvements lately to improv overall stability

[Ritaja]

HI @renardeinside, thanks did a git pull on master, removed/deleted old app. Did a uv build and then re-deployed. Still same challenge, app is in "crashed" state with no logs.

[tzhang1998]

I have the same issue. It was working correctly when it initially deployed couple of weeks ago, I "stop" the app for a few days. Today, it crashed upon "start up".

Tried "delete/deploy the app" but with no luck.

also, deployment with "bundle" option failed with terraform error "I upgraded my cli to 0.258" (worked fine with cli version 0.235).