Playwright MCP sidecar crashes: unknown option '--transport' #41

New Issue

2026-02-22T19:45:40Z

cpfarhood commented

2026-02-22 19:45:40 +00:00

(Migrated from github.com)

Summary

In chart v0.4.0, the playwright MCP sidecar image was fixed to mcr.microsoft.com/playwright/mcp:latest, but the container crashes on startup:

error: unknown option '--transport'

The chart appears to pass a --transport argument that this image doesn't support.

Workaround

Disable the playwright sidecar:

mcp:
  sidecars:
    playwright:
      enabled: false

## Summary In chart v0.4.0, the playwright MCP sidecar image was fixed to `mcr.microsoft.com/playwright/mcp:latest`, but the container crashes on startup: ``` error: unknown option '--transport' ``` The chart appears to pass a `--transport` argument that this image doesn't support. ## Related - #40 (original MCP sidecar image issues) ## Workaround Disable the playwright sidecar: ```yaml mcp: sidecars: playwright: enabled: false ```

cpfarhood commented

2026-02-22 20:04:27 +00:00

(Migrated from github.com)

Fixed in v0.4.1. The Playwright MCP image (mcr.microsoft.com/playwright/mcp) doesn't support --transport. Changed to use node cli.js --headless --browser chromium --no-sandbox --port <port> for SSE mode.

Fixed in v0.4.1. The Playwright MCP image (`mcr.microsoft.com/playwright/mcp`) doesn't support `--transport`. Changed to use `node cli.js --headless --browser chromium --no-sandbox --port <port>` for SSE mode.

cpfarhood commented

2026-02-22 20:27:39 +00:00

(Migrated from github.com)

The fix in v0.4.1 doesn't seem to work. Still getting the same error:

error: unknown option '--transport'

The mcr.microsoft.com/playwright/mcp:latest image still doesn't support the --transport argument that the chart passes to it.

The fix in v0.4.1 doesn't seem to work. Still getting the same error: ``` error: unknown option '--transport' ``` The mcr.microsoft.com/playwright/mcp:latest image still doesn't support the `--transport` argument that the chart passes to it.

cpfarhood commented

2026-02-22 20:35:49 +00:00

(Migrated from github.com)

Good progress with v0.4.2! The --transport error is now fixed and the playwright container starts successfully.

However, there's a new issue: liveness/readiness probe failures:

Liveness probe failed: dial tcp 172.18.1.25:8086: connect: connection refused
Readiness probe failed: dial tcp 172.18.1.25:8086: connect: connection refused

The container starts and outputs:

{
  "protocol": "2024-11-05",
  "serverInfo": {
    "name": "playwright",
    "version": "0.7.1"
  },
  "capabilities": {
    "prompts": {},
    "resources": {},
    "tools": {
      "listChanged": true
    }
  },
  "instructions": "I am a Playwright MCP server that can help you with web automation tasks. Available tools: screenshot, click, fill, keyboard_type, wait_for_selector, get_text, get_attribute, evaluate_js, navigate_to, go_back, go_forward, reload, set_viewport_size, close_page. When using tools, remember to take a screenshot first to see the current page state.",
  "meta": {
    "url": "http://localhost:8086/mcp"
  }
}
For legacy SSE transport support, you can use the /sse endpoint instead.

But the probe can't connect to port 8086. The service might not be binding to the right interface or there could be a probe configuration issue.

Good progress with v0.4.2! The `--transport` error is now fixed and the playwright container starts successfully. However, there's a new issue: **liveness/readiness probe failures**: ``` Liveness probe failed: dial tcp 172.18.1.25:8086: connect: connection refused Readiness probe failed: dial tcp 172.18.1.25:8086: connect: connection refused ``` The container starts and outputs: ```json { "protocol": "2024-11-05", "serverInfo": { "name": "playwright", "version": "0.7.1" }, "capabilities": { "prompts": {}, "resources": {}, "tools": { "listChanged": true } }, "instructions": "I am a Playwright MCP server that can help you with web automation tasks. Available tools: screenshot, click, fill, keyboard_type, wait_for_selector, get_text, get_attribute, evaluate_js, navigate_to, go_back, go_forward, reload, set_viewport_size, close_page. When using tools, remember to take a screenshot first to see the current page state.", "meta": { "url": "http://localhost:8086/mcp" } } For legacy SSE transport support, you can use the /sse endpoint instead. ``` But the probe can't connect to port 8086. The service might not be binding to the right interface or there could be a probe configuration issue.

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Reference: farhoodlabs/devcontainer#41