MM Error Handling

Error response format

All API errors return a JSON body:

{
  "detail": "Invalid or missing API key"
}

Validation errors include location details:

{
  "detail": [
    {
      "loc": ["query", "fixtureId"],
      "msg": "Field required",
      "type": "missing"
    }
  ]
}

HTTP status codes

Status	Description
`200`	Success
`401`	Unauthorized — invalid or missing API key (must be valid UUID)
`404`	Not found — resource does not exist
`409`	Conflict — action blocked by current state (e.g. deactivating with open orders, duplicate resource)
`422`	Validation error — request parameters failed validation
`426`	Upgrade required — WebSocket endpoint called via HTTP
`429`	Rate limited — exceeded 2,000 requests/minute
`500`	Internal server error
`502`	Bad gateway — partial failure (e.g. cancel request succeeded for some orders but not all)

Rate limiting

The MM API enforces 2,000 requests/minute per client API key. When rate limited, the API returns 429 Too Many Requests. Implement exponential backoff in your retry logic (wait 1s, 2s, 4s, etc.).

Common errors

Authentication (401)

Your API key is missing, invalid, or not in UUID format.

# Correct
curl -H "X-API-Key: YOUR_API_KEY" \
  https://mmapi.55-tech.com/api/v1/trading/status

# Wrong header name — returns 401
curl -H "Authorization: Bearer your-key" \
  https://mmapi.55-tech.com/api/v1/trading/status

# Missing header — returns 401
curl https://mmapi.55-tech.com/api/v1/trading/status

Not found (404)

The requested resource doesn’t exist:

curl -X POST -H "X-API-Key: YOUR_API_KEY" \
  https://mmapi.55-tech.com/api/v1/orders/999999/cancel
# Returns: 404

Validation errors (422)

Required query parameters are missing or have invalid values. Check the loc field to identify the problematic parameter.

WebSocket upgrade (426)

If you call the WebSocket endpoint via HTTP instead of upgrading to a WebSocket connection, you receive a 426 Upgrade Required.

WebSocket errors

When subscribing to the WebSocket, these error messages may be returned:

Error	Description
`apiKey required`	No `apiKey` field in subscribe message
`Invalid apiKey format`	Not a valid UUID
`Invalid API key`	Key not found or client inactive
`Connection limit exceeded`	Already at 5 active connections for this key

Getting Started

Reference

Error response format

HTTP status codes

Rate limiting

Common errors

Authentication (401)

Not found (404)

Validation errors (422)

WebSocket upgrade (426)

WebSocket errors

​Error response format

​HTTP status codes

​Rate limiting

​Common errors

​Authentication (401)

​Not found (404)

​Validation errors (422)

​WebSocket upgrade (426)

​WebSocket errors

Error response format

HTTP status codes

Rate limiting

Common errors

Authentication (401)

Not found (404)

Validation errors (422)

WebSocket upgrade (426)

WebSocket errors