<blockquote>
<p>Is 0.16777215 BTC hardcoded in Electrum or is it determined by the testnet itself?</p>
</blockquote>
<p>There's no such hard coded value in Electrum. The limit is imposed by the <a href="https://github.com/lightning/bolts/blob/b201efe0546120c14bf154ce5f4e18da7243fe7a/02-peer-protocol.md#requirements-9" rel="nofollow noreferrer">Lightning protocol</a>:</p>
<blockquote>
<p>for channels with <code>chain_hash</code> identifying the Bitcoin blockchain, if the four most significant bytes of <code>amount_msat</code> are not 0:
MUST fail the channel.</p>
</blockquote>

CC BY-SA 4.0
2022-06-17T10:52:34.390Z
2022-06-17T10:52:34.390Z
Angelo
<p>Using Electrum desktop wallet connected to the testnet, when trying to open a channel  with the amount exceeding 0.16777215 BTC I get the following:</p>
<blockquote>
<p>Could not open channel. Exception('Requested channel capacity is over protocol allowed maximum')</p>
</blockquote>
<p>Is 0.16777215 BTC hardcoded in Electrum or is it determined by the testnet itself?
I noticed that on the mainnet the maximum capacity is siginificatly higher as some exchanges allow LN withdrawals of 0.5 BTC.</p>

<electrum><testnet><ln-opening-channels>
What is the maximum channel capacity allowed on the Bitcoin testnet?
John Smith
# What is the maximum channel capacity allowed on the Bitcoin testnet?

(Asked by: username_0 on 2021-01-22)

Using Electrum desktop wallet connected to the testnet, when trying to open a channel with the amount exceeding 0.16777215 BTC I get the following:

> Could not open channel. Exception('Requested channel capacity is over protocol allowed maximum')

Is 0.16777215 BTC hardcoded in Electrum or is it determined by the testnet itself?
I noticed that on the mainnet the maximum capacity is siginificatly higher as some exchanges allow LN withdrawals of 0.5 BTC.

**Tags:** electrum, testnet, ln-opening-channels


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## 1 answers

### Answer by username_1 on 2022-06-17. Score: 1

> Is 0.16777215 BTC hardcoded in Electrum or is it determined by the testnet itself?

There's no such hard coded value in Electrum. The limit is imposed by the [Lightning protocol](https://github.com/lightning/bolts/blob/b201efe0546120c14bf154ce5f4e18da7243fe7a/02-peer-protocol.md#requirements-9):

> for channels with `chain_hash` identifying the Bitcoin blockchain, if the four most significant bytes of `amount_msat` are not 0:
> MUST fail the channel.


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