BlockCypher API: 'Error no data to embed for OP_RETURN output 1.'

[gregnomis]

Hey guys, I am baffled on this one.
I successfully create a tx skeleton to Blockcypher's expected format with null-data (OP_RETURN). The data is in hex, and value set to 0. Yet I still get:
Error creating transaction skeleton: { errors: [ { error: 'Error no data to embed for OP_RETURN output 1.' } ],

Here is my log:
Received hash to submit: 84e4111fc915e6465cc024512b590a93e7fd99bdc4b50f15e45b7cae3c7588ea
Creating and sending transaction...
Preparing to create transaction skeleton.
Creating transaction skeleton with requestBody: {
"inputs": [
{
"addresses": [
"bc1qu05e8nvpy5f9pyyxs9c76drvksfqsy6gztf70u"
]
}
],
"outputs": [
{
"addresses": [
"bc1quul9kxpd63mghcgj6h5gc7g5c2zqmnmzex94ml"
],
"value": 700
},
{
"script_type": "null-data",
"data": "84e4111fc915e6465cc024512b590a93e7fd99bdc4b50f15e45b7cae3c7588ea",
"value": 0
}
],
"token": "8a2fe74a171c4f379ad2bc3b615510ef"
}

Modified addresses and tokens for obvious reasons.

Any idea? The hash is in the correct hex format, I don't understand why its saying there's no data to embed.
Thanks!

[gregnomis]

Well, although adding the null-data in hex didn't work, BlockCypher also accepts them as ASCII. So that's what I did and it worked:
// Modified createTransactionSkeleton function
async function createTransactionSkeleton(dataHash) {
console.log('Preparing to create transaction skeleton.');

// Convert hash to ASCII-safe Base64 encoding
const dataAscii = Buffer.from(dataHash, 'hex').toString('base64');

const inputs = [{ addresses: [address] }]; 
const outputs = [
    {
        addresses: ['bc1quul9k5pd63mgh4gj6h5gc7g5c24qmnmzex94hl'],
        value: 700 
    },
    {
        script_type: "null-data",
        data_string: dataAscii, // Use data_string field for ASCII representation instead of hex
        value: 0 
    }
];

const requestBody = {
    inputs: inputs,
    outputs: outputs,
    token: blockCypherToken
};

console.log('Creating transaction skeleton with requestBody:', JSON.stringify(requestBody, null, 2));

const url = `https://api.blockcypher.com/v1/btc/main/txs/new`;

try {
    const response = await axios.post(url, requestBody);
    console.log('Transaction skeleton created successfully:', response.data);
    return response.data; 
} catch (error) {
    console.error('Error creating transaction skeleton:', error.response ? error.response.data : error);
    throw error;
}

}

It seems that attaching null-data in hex-encoded format is buggy or glitch, just a heads up. ASCII format works.