user116589: I'm trying to figure out how to send tiny transactions, like 10 cents.  Coinbase says the minimum is .001btc.  That seems rather large.  Is that just a coinbase requirement?
Also, my blockchain wallet says that my bitcoincore wallet receiving qr code is an "Invalid Bitcoin address: "  Why?

user13866: 
Also, my blockchain wallet says that my bitcoincore wallet receiving qr code is an "Invalid Bitcoin address: " Why?

It might be that your Blockchain.com wallet doesn't yet support the Bech32 address format (addresses starting bc1...) introduced four years ago.

116589: <p>I'm trying to figure out how to send tiny transactions, like 10 cents.  Coinbase says the minimum is .001btc.  That seems rather large.  Is that just a coinbase requirement?</p>
<p>Also, my blockchain wallet says that my bitcoincore wallet receiving qr code is an &quot;Invalid Bitcoin address: &quot;  Why?</p>
 13866: <blockquote>
<p><strong>Also, my blockchain wallet says that my bitcoincore wallet receiving qr code is an &quot;Invalid Bitcoin address: &quot; Why?</strong></p>
</blockquote>
<p>It might be that your Blockchain.com wallet doesn't yet <a href="https://en.bitcoin.it/wiki/Bech32_adoption" rel="nofollow noreferrer">support</a> the <a href="https://en.bitcoin.it/wiki/Bech32" rel="nofollow noreferrer">Bech32</a> address format (addresses starting <code>bc1...</code>) introduced <em>four years ago</em>.</p>
