MPC signing failed for Embedded Wallets (NCW) sandbox enviroment

Developer Discussion
1

Hi,
I’m integrating Embedded Wallets. Things is working fine so far and I could generate mpc keys and sign transactions.
But suddenly it stops working since yesterday with all provisioned embedded wallets on both android and ios.
And also I couldn’t generate new mpc keys for new wallet anymore.
I updated the FireblockSdk for ios to the latest (2.9.14) but that doesn’t help either

Screenshot 2025-09-16 at 17.01.52
Screenshot 2025-09-16 at 17.01.521920×1896 181 KB

{
    "operationName": "rpc",
    "variables": {
        "input": {
            "deviceId": "27c1361b-968e-4143-9693-6fd8a14832e8",
            "message": "{\"params\":[{\"ack\":true,\"poll\":false,\"msg\":{\"payload\":{\"metadata\":{\"immediate\":true},\"recipients\":[],\"cosignerVersion\":6,\"transaction\":\"301e48c2-16e9-4c6d-8cf6-93b876d957b3\",\"payload\":\"{\\\"keyId\\\":\\\"301e48c2-16e9-4c6d-8cf6-93b876d957b3\\\",\\\"reason\\\":\\\"ERROR_UNEXPECTED\\\",\\\"txId\\\":\\\"301e48c2-16e9-4c6d-8cf6-93b876d957b3\\\"}\",\"version\":6,\"sig\":\"\",\"phase\":\"MPC_ERROR_SIGNING\",\"sender\":\"43710789949070\"}}}],\"method\":\"broadcast_mpc_msg\",\"headers\":{\"platformType\":\"iOS\",\"mpcVersion\":\"6\",\"sdkVersion\":\"2.9.14\",\"physicalDeviceId\":\"b3040c8b-d452-487b-8155-f6306a59a624\"}}"
        }
    },
    "query": "mutation rpc($input: RpcInput!) {\n  rpc(input: $input)\n}"
}

I got the “PENDING_SIGNATURE” webhooks

{
    "type": "TRANSACTION_STATUS_UPDATED",
    "tenantId": "394e465f-f696-446d-9eac-d33f0479ee38",
    "timestamp": 1758045184118,
    "data": {
        "id": "defd82f1-90f0-46de-b43f-ffe55682b805",
        "createdAt": 1758045172732,
        "lastUpdated": 1758045175139,
        "assetId": "ETH_TEST5",
        "source": {
            "id": "0",
            "type": "END_USER_WALLET",
            "name": "",
            "subType": "",
            "walletId": "16e9c21a-f11e-408a-a33a-da144f0d2d12"
        },
        "destination": {
            "id": null,
            "type": "ONE_TIME_ADDRESS",
            "name": "N/A",
            "subType": ""
        },
        "amount": 0.001,
        "sourceAddress": "",
        "destinationAddress": "0x6eF27528EBE0288c2F51425B9a9D027c249C3ecc",
        "destinationAddressDescription": "",
        "destinationTag": "",
        "status": "PENDING_SIGNATURE",
        "txHash": "",
        "subStatus": "",
        "signedBy": [],
        "createdBy": "1c07f9a7-a6b9-4772-8db3-d9a8f6aae144",
        "rejectedBy": "",
        "amountUSD": 4.5,
        "addressType": "",
        "note": "API Transaction by 6794fc0b0f878b0d52342304",
        "exchangeTxId": "",
        "requestedAmount": 0.001,
        "feeCurrency": "ETH_TEST5",
        "operation": "TRANSFER",
        "customerRefId": null,
        "amountInfo": {
            "amount": "0.001",
            "requestedAmount": "0.001",
            "amountUSD": "4.50"
        },
        "feeInfo": {},
        "destinations": [],
        "externalTxId": null,
        "blockInfo": {},
        "signedMessages": [],
        "assetType": "BASE_ASSET"
    }
}

but then it got stuck to move forward these polling steps with empty response

{
  "params": [
    {
      "txId": "defd82f1-90f0-46de-b43f-ffe55682b805"
    }
  ],
  "method": "poll_mpc_msg",
  "headers": {
    "physicalDeviceId": "b3040c8b-d452-487b-8155-f6306a59a624",
    "mpcVersion": "6",
    "sdkVersion": "2.9.14",
    "platformType": "iOS"
  }
}

then timeout and failed with these response

{
    "data": {
        "rpc": {
            "result": {
                "id": "965e0ce84d1b84685c30c4dfa1100df5a8ec70ce73d67ef360ba20d9981efad7",
                "txId": "defd82f1-90f0-46de-b43f-ffe55682b805",
                "rawMessage": "truncated...",
                "iat": 1758045357,
                "type": "MPC_STOP_SIGNING"
            }
        }
    }

It worked perfectly fine for me last week so it’s a bit weird. Please help.