<p><code>bitcoind</code> uses transactions it relays (and later see as mined) to estimate the feerate to set for transactions its wallet creates.</p>
<p>On regtest, you don't relay then mine enough transactions so <code>bitcoind</code>'s estimation buckets are not filled enough to give a reliable estimate. Without such an estimate the wallet, out of safety, prefer not to create any transaction unless you explicitly tell it what fee to use when fee estimation isn't available.</p>
<p>This &quot;fall back feerate&quot; can be set up at <code>bitcoind</code>'s startup with the <code>fallbackfee</code> startup option, expressed in <code>BTC/kB</code>.</p>
<blockquote>
<pre><code>   -fallbackfee=&lt;amt&gt;

         A fee rate (in BTC/kB) that will be used when fee estimation has
         insufficient data. 0 to entirely disable  the  fallbackfee  fea‐
         ture.  (default: 0.00)
</code></pre>
</blockquote>
<p>Alternatively, crafting transactions on different nodes of your regtest network and getting them mined will result in estimation buckets to be filled.</p>

CC BY-SA 4.0
2020-07-27T10:35:29.123Z
2020-07-27T10:35:29.123Z
Antoine Poinsot
<p>You could enable <code>-fallbackfee</code> (as darosior says) but the easiest or quickest way to resolve this is to set a fee. In this example we are setting a fee of 1 satoshis per byte.</p>
<pre><code>./bitcoin-cli sendtoaddress &quot;bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl&quot; 0.1 &quot;&quot; &quot;&quot; false true 1 sat/B
</code></pre>
<p>If you do</p>
<pre><code>./bitcoin-cli -regtest help sendtoaddress
</code></pre>
<p>you will see what those arguments after the regtest address represent.</p>
<p>Alternatively if you want to set the fallback fee see this StackExchange <a href="https://bitcoin.stackexchange.com/questions/91533/fallbackfee-option-in-sendtoaddress">question</a>.</p>
<p>This PR <a href="https://github.com/bitcoin/bitcoin/pull/16524" rel="nofollow noreferrer">16524</a> merged in October 2019 disabled <code>-fallbackfee</code> across all chains (mainnet, testnet, regtest) by default.</p>

CC BY-SA 4.0
2020-10-05T15:05:38.610Z
2020-10-05T15:05:38.610Z
Michael Folkson
<p>You can set the fee rate easily when using named parameters:</p>
<pre><code>bitcoin-cli -regtest -named sendtoaddress \
  address=bcrt1qd3jck0lv87yuk25tk3xy5rqq67apwasee874xk \
  amount=25 \
  fee_rate=100
</code></pre>

CC BY-SA 4.0
2021-01-24T21:30:05.737Z
2021-01-24T21:30:05.737Z
schmijos
<p>I have been doing an assignment on Bitcoin Core 0.20. Now every time I try to do a transaction:</p>
<pre><code>Apples-iMac:bitcoin apple$ bitcoin-cli -regtest sendtoaddress bcrt1qd3jck0lv87yuk25tk3xy5rqq67apwasee874xk 25 
error code: -4
error message:
Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.
</code></pre>
<p>Can some one help me - what should I change? Please give a step by step guide as I am a complete newcomer.</p>

<bitcoin-core><transaction-fees><bitcoin-core-development><regtest><signet>
When using bitcoin-cli I get an error regarding fallback fees when trying to send regtest Bitcoin. How do I resolve this?
Deep
# When using bitcoin-cli I get an error regarding fallback fees when trying to send regtest Bitcoin. How do I resolve this?

(Asked by: username_0 on 2020-07-24)

I have been doing an assignment on Bitcoin Core 0.20. Now every time I try to do a transaction:
Apples-iMac:bitcoin apple$ bitcoin-cli -regtest sendtoaddress bcrt1qd3jck0lv87yuk25tk3xy5rqq67apwasee874xk 25 
error code: -4
error message:
Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.

Can some one help me - what should I change? Please give a step by step guide as I am a complete newcomer.

**Tags:** bitcoin-core, transaction-fees, bitcoin-core-development, regtest, signet


---

## 3 answers

### Answer by username_1 on 2020-07-27. Score: 3

bitcoind uses transactions it relays (and later see as mined) to estimate the feerate to set for transactions its wallet creates.
On regtest, you don't relay then mine enough transactions so bitcoind's estimation buckets are not filled enough to give a reliable estimate. Without such an estimate the wallet, out of safety, prefer not to create any transaction unless you explicitly tell it what fee to use when fee estimation isn't available.
This "fall back feerate" can be set up at bitcoind's startup with the fallbackfee startup option, expressed in BTC/kB.

   -fallbackfee=

         A fee rate (in BTC/kB) that will be used when fee estimation has
         insufficient data. 0 to entirely disable  the  fallbackfee  fea‐
         ture.  (default: 0.00)


Alternatively, crafting transactions on different nodes of your regtest network and getting them mined will result in estimation buckets to be filled.


---

### Answer by username_2 on 2020-10-05. Score: 2

You could enable -fallbackfee (as darosior says) but the easiest or quickest way to resolve this is to set a fee. In this example we are setting a fee of 1 satoshis per byte.
./bitcoin-cli sendtoaddress "bc1q09vm5lfy0j5reeulh4x5752q25uqqvz34hufdl" 0.1 "" "" false true 1 sat/B

If you do
./bitcoin-cli -regtest help sendtoaddress

you will see what those arguments after the regtest address represent.
Alternatively if you want to set the fallback fee see this StackExchange question.
This PR 16524 merged in October 2019 disabled -fallbackfee across all chains (mainnet, testnet, regtest) by default.


---

### Answer by username_3 on 2021-01-24. Score: 2

You can set the fee rate easily when using named parameters:
bitcoin-cli -regtest -named sendtoaddress \
  address=bcrt1qd3jck0lv87yuk25tk3xy5rqq67apwasee874xk \
  amount=25 \
  fee_rate=100


---

