user51663: Looking to fetch the UTXOs for a given address and can't seem to find the correct command syntax.
Here is an implementation in bitcoin-core via javascript, but I also experience the same on bitcoin-cli
const descriptorAttempts = [
    '{ desc: addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo) }', 
    '{ "desc": "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" }', 
    '"desc": "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)"', 
    "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)", 
    "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)", 
    "addr=34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo", 
    "34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo", 
    "{ addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo) }", 
    "{ addr: 34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo }",
    "{\"desc\": \"addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)\"}",
    '\"{\"desc": \"addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)\"}\"',
    '"{"desc": "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)"}"',
    '"{"desc": "addr("34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo")"}"',
    '\"{\"desc": \"addr(\"34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo\")\"}\"',
    '"desc" => "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)"',
    '[ "desc" => "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" ]',
    { "desc" : "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" },
    { desc : "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" }
]

descriptorAttempts.forEach(attempt => {
    client.command('scantxoutset', 'start', [ attempt ])
    .then((res) => {
        console.log("Success! ")
        console.log(res)
    })
    .catch((error) => {
        console.log("Failed attempt of -> " + attempt)
        // console.log(error)
    })
})

All result in RpcError: Invalid descriptor

user51663: I resolved this.
Here is the functional command: 
client.command('scantxoutset', 'start' ['addr(mfe87Qheq7SSveCDedyDUBEjMD9tgzRiU7)']) <!-- Address is valid. This address: '34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo' is invalid

The issue is that the address was invalid. Using a valid address, I can ensure that this works.

user48884: You are trying to use a mainnet encoded address on testnet. That is not valid. You need to use a testnet encoded address.
The testnet form of the address you are trying to use is 2MvX28fMpoipKxqaxo6pN1CH4QjB5t9qpr8.

51663: <p>Looking to fetch the UTXOs for a given address and can't seem to find the correct command syntax.</p>

<p>Here is an implementation in bitcoin-core via javascript, but I also experience the same on bitcoin-cli</p>

<pre><code>const descriptorAttempts = [
    '{ desc: addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo) }', 
    '{ "desc": "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" }', 
    '"desc": "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)"', 
    "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)", 
    "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)", 
    "addr=34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo", 
    "34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo", 
    "{ addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo) }", 
    "{ addr: 34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo }",
    "{\"desc\": \"addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)\"}",
    '\"{\"desc": \"addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)\"}\"',
    '"{"desc": "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)"}"',
    '"{"desc": "addr("34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo")"}"',
    '\"{\"desc": \"addr(\"34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo\")\"}\"',
    '"desc" =&gt; "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)"',
    '[ "desc" =&gt; "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" ]',
    { "desc" : "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" },
    { desc : "addr(34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo)" }
]

descriptorAttempts.forEach(attempt =&gt; {
    client.command('scantxoutset', 'start', [ attempt ])
    .then((res) =&gt; {
        console.log("Success! ")
        console.log(res)
    })
    .catch((error) =&gt; {
        console.log("Failed attempt of -&gt; " + attempt)
        // console.log(error)
    })
})
</code></pre>

<p>All result in <code>RpcError: Invalid descriptor</code></p>
 51663: <p>I resolved this.</p>

<p>Here is the functional command: </p>

<pre><code>client.command('scantxoutset', 'start' ['addr(mfe87Qheq7SSveCDedyDUBEjMD9tgzRiU7)']) &lt;!-- Address is valid. This address: '34xp4vRoCGJym3xR7yCVPFHoCNxv4Twseo' is invalid
</code></pre>

<p>The issue is that the address was invalid. Using a valid address, I can ensure that this works.</p>
 48884: <p>You are trying to use a mainnet encoded address on testnet. That is not valid. You need to use a testnet encoded address.</p>

<p>The testnet form of the address you are trying to use is <code>2MvX28fMpoipKxqaxo6pN1CH4QjB5t9qpr8</code>.</p>
