Setting Up Your Bitcoin Node Step by Step

By the end of this lesson you will have a Bitcoin node running at home on a Raspberry Pi, checking every block for itself, with your own wallet connected to it instead of to a stranger’s server. You will also know how to check that the software you download arrived intact (and what that check can’t prove), how to add Lightning without getting stuck unable to receive, and which Lightning backup protects your money and which copy can cost you all of it.

In the previous lessons you saw why running your own node matters and compared the main node platforms. Here we follow one setup from start to finish: umbrelOS on a Raspberry Pi 5, the most common first node. umbrelOS is Umbrel’s free operating system that turns a small computer into a home server with an app store. The steps match umbrelOS 2.0.1, the current version in November 2026; our Umbrel review covers the rest of what it does. If you chose another platform, the table below tells you what changes.

Affiliate disclosure: the Umbrel Home link in the FAQ at the end of this lesson is an affiliate link (we may earn a commission); the Start9 Server One link is not. Building your own node, as this lesson shows, is what we recommend for most readers.

What you are building

A full node is a computer running Bitcoin software, here Bitcoin Core, that downloads every block since 2009 and checks each one against Bitcoin’s rules by itself. Once it has done that, nobody can lie to your wallet about your balance or about whether a payment really arrived.

Hands-on work takes 30 to 60 minutes. The long part, downloading and checking the whole blockchain, then runs on its own for a few days. The steps:

1. Download umbrelOS and check the download
2. Write it to a microSD card and start the Pi
3. Install Bitcoin Core and move it to the SSD
4. Let it sync
5. Connect your wallet
6. Add Lightning (optional)
7. Back up and keep it up to date

On a different platform?

Platform	Runs on	How you reach it the first time
umbrelOS 2.0 (this lesson)	Raspberry Pi 5 or 4, from a microSD card; Intel or AMD PCs	http://umbrel.local in a browser
StartOS 0.4.1	Intel and AMD PCs, and computers with ARM64 or RISC-V processors (other chip designs, common in small boards); among Raspberry Pis, the Pi 4 only	http://start.local for setup, then your server’s own name.local address once you have installed its certificate on your computer (Start9’s install guide)
RaspiBlitz 1.12	Raspberry Pi, from a microSD card of 64 GB or more	Setup runs in a terminal over SSH, a text connection to the Pi; the fatpack image, meant for beginners, also offers it in a browser at the Pi’s IP address (RaspiBlitz docs; also our RaspiBlitz tutorial)
myNode	Raspberry Pi 5 or 4, or a mini-PC, booting from a USB stick of 32 GB or more	http://mynode.local (myNode’s getting started guide)

Whatever you chose, the ideas are the same: check the download, let the node sync, point your wallet at it, keep your Lightning channel backup off the device, and install updates yourself.

What You’ll Need

Part	Get this	Why
Computer	Raspberry Pi 5 with 8 GB of memory, or an Intel or AMD mini-PC, which is faster still. Not a Pi 4 for this setup: Umbrel recommends the Pi 5 because USB drives, like the SSD used here, can make a Pi 4 crash (Umbrel’s Raspberry Pi guide)	Checking every block since 2009 is real work for a small computer, and the node has to run reliably around the clock
Drive	Raspberry Pi: a 2 TB SSD (solid-state drive: fast storage with no moving parts) in a USB 3 enclosure. Mini-PC: a 2 TB internal SSD (an external drive leaves the Electrum server stuck on the small internal one)	The blocks don’t fit on a card, and a mechanical hard drive is too slow: the first sync would take weeks
microSD card	32 GB or bigger, from a known brand	umbrelOS runs from it and keeps your apps on it
Power supply	The official Raspberry Pi 27 W supply (5 V, 5 A)	With any supply that can’t deliver 5 A, a Pi 5 limits its USB devices to 600 mA in total (Raspberry Pi docs), which can starve the SSD
Network	An Ethernet cable to your router	Wi-Fi drops slow the sync and can disrupt Lightning
Case	One with a heatsink or a fan	The processor works hard for days during the first sync

We don’t list prices because they moved a lot in 2026: Raspberry Pi has raised the price of its boards with 2 GB or more of memory several times since December 2025, as memory became more expensive (Raspberry Pi’s announcement). Check current prices before you buy. For more on hardware and your home network, see our guide to running Bitcoin nodes at home.

Why 2 TB, and why pruning is not the way out

Bitcoin’s blocks took about 779 GB on 28 October 2026 and grow by roughly 80 GB a year (blockchain.com chart). That counts only the raw blocks. On disk, Bitcoin Core also keeps undo data (what it needs to reverse a block if another chain wins) and its list of unspent coins, so Bitcoin Core itself plans for about 900 GB of disk today (its built-in estimate, in version 32.1). On Umbrel, the Bitcoin Node app also builds a transaction index and a block-filter index by default (its settings), which add tens of gigabytes more. So on Umbrel a 1 TB drive is already too small. On a mini-PC you may also add an Electrum server (an address index that most wallets use, explained in Step 5), which needs room on the same drive: Electrs says its index takes about 10% of the blockchain’s size (Electrs README), and Fulcrum asked for 133 GB of disk space back in August 2023 (Fulcrum README).

Pruning is a setting that makes Bitcoin Core delete old blocks after checking them, so the node needs roughly 15 to 20 GB instead of about 900 GB. (It still keeps its list of every coin not yet spent, which alone takes over 10 GB.) It doesn’t help here. Electrs and Fulcrum, the Electrum servers in Step 5, don’t work with a pruned node (Electrs, Fulcrum), and a wallet connected straight to Bitcoin Core can’t look further back than the blocks a pruned node kept (Sparrow’s guide). A pruned node still downloads every block once. And turning pruning off later means downloading the whole blockchain again. Buy the 2 TB drive now.

Step 1: Download umbrelOS and Check the Download

Download umbrelos-pi.img.zip, the version for the Raspberry Pi 5 and Pi 4, from umbrel.com/downloads. It is an image: an exact copy of a whole disk that you will write onto the card.

On a Pi 4, first update its bootloader, the small piece of firmware that starts the board. Umbrel says many Pi 4 boards won’t start umbrelOS 2.0 without it; its Raspberry Pi guide links to the steps, which take about five minutes. A Pi 5 usually starts without the update, but some early Pi 5 boards need it too: if yours doesn’t start umbrelOS in Step 2, update its bootloader the same way.

Verify the download

You are setting up a node so that you don’t have to trust anyone, and the first thing you run on it is a file from the internet. A checksum is the first check. A SHA-256 checksum is a 64-character fingerprint calculated from every byte of a file. Change one byte and the fingerprint changes completely. If your file’s fingerprint matches the one in Umbrel’s list, your download is complete and undamaged.

1. Get Umbrel’s list of fingerprints from the same folder as your image. The download link on umbrel.com/downloads contains the version, for example https://download.umbrel.com/release/2.0.1/umbrelos-pi.img.zip in November 2026, so the list for that version is at https://download.umbrel.com/release/2.0.1/SHA256SUMS: replace the file name with SHA256SUMS. (If your link had latest instead of a number, open …/release/latest/SHA256SUMS straight after downloading, before a newer version replaces it. Each version’s notes on Umbrel’s releases page link to the same list.) Each line is a fingerprint followed by a file name. Find the line that ends in umbrelos-pi.img.zip.
2. Calculate your own file’s fingerprint:
   • Mac: open Terminal and type shasum -a 256 ~/Downloads/umbrelos-pi.img.zip
   • Linux: sha256sum ~/Downloads/umbrelos-pi.img.zip
   • Windows: open PowerShell and type Get-FileHash $HOME\Downloads\umbrelos-pi.img.zip. It prints the code in capital letters; that’s fine, because only the letters and digits matter, not their case.
3. Compare the two codes. If they match, go on. If they don’t, delete the file, download it again and check again. Never write a file that fails.

What this proves, and what it doesn’t. Umbrel’s list comes from the same download server as the image, and Umbrel doesn’t sign it. So the check reliably catches a damaged or incomplete download, but it can’t show that nobody swapped the file: anyone able to replace the image on that server could replace the list too. (On the way to you, the file is already protected by the browser’s HTTPS connection.) A signature closes that gap, because only the developers’ private key can produce it; StartOS and RaspiBlitz sign their releases. With umbrelOS, you are trusting Umbrel’s download server. Our lesson on verifying Bitcoin software before you install it shows how a signature check works; use it for the software that will hold your keys, such as Sparrow.

Step 2: Write the Card and Start the Pi

1. Open Raspberry Pi Imager or balenaEtcher (both free), choose the file you downloaded, then choose your microSD card. Check the target twice: whatever drive you pick is erased.
2. Put the card in the Pi and plug in the Ethernet cable. Leave the SSD unplugged for now.
3. Plug in the power and wait a few minutes for the first start.
4. On a computer on the same network, open http://umbrel.local. If it doesn’t load, find the Pi’s IP address in your router’s list of connected devices and open http:// followed by that address.
5. Create your account with a strong, unique password, and keep it in a password manager.

If the SSD was plugged in during setup, umbrelOS asks you to Select main storage. Choose the SD card. umbrelOS never formats a connected drive during setup.

Step 3: Install Bitcoin Core and Move It to the SSD

umbrelOS 2.0 runs from the card and keeps apps and their data there too, and a 32 GB card can’t hold 779 GB of blocks. So you install Bitcoin Core as an app and move that app to the SSD before it starts filling the card.

1. Plug the SSD into one of the blue USB 3 ports. It appears under External storage in Files.
2. An app can only move to a drive formatted as ext4, the usual Linux disk format. If yours isn’t, right-click it under External storage, choose Format and pick ext4. This erases the drive.
3. Open the App Store and install Bitcoin Node, Umbrel’s app that runs Bitcoin Core.
4. Right-click its icon, choose Settings, and under Storage choose App storage → Move to move it to the SSD. Do it straight away.

The SSD must stay connected while the app runs. Apps on an external drive are left out of umbrelOS Backups, which is fine for Bitcoin Node: blocks can always be downloaded again (Umbrel’s external storage guide). Your other apps stay on the card, and Umbrel warns that microSD cards wear out over time. Set up umbrelOS Backups to a USB drive, a NAS (a storage box on your home network) or another Umbrel.

Step 4: Let It Sync

Bitcoin Core now does its Initial Block Download (IBD): it downloads every block from the first one, mined in January 2009, and checks each one against Bitcoin’s rules itself: no coins created from nothing, nothing spent twice, and each block backed by the mining work it claims. To save time, by default it doesn’t re-check the signatures in one block that each Bitcoin Core release marks as valid, or in any block before it, as long as that block is part of the chain it is downloading. This setting is called assumevalid (developers review that block before each release; assumevalid=0 checks them all, but the sync takes longer). This is the step that makes the node yours. A light wallet asks someone else what happened; your node has checked the whole history on your own hardware.

• How long: roughly two to four days on a Raspberry Pi 5, longer on a Pi 4, and a day or two on a mini-PC with a fast NVMe drive (an SSD that plugs straight into the computer’s board). The progress shows in the Bitcoin Node app.
• Leave it alone: keep it running. If you have to turn it off, shut it down from the dashboard instead of pulling the plug, because a sudden power cut can corrupt the card or Bitcoin Core’s data.
• Keep it cool: if the Pi is too hot to touch comfortably, improve the airflow.
• Data use: the first sync downloads about 800 GB. After that, bitcoin.org puts downloads at about 20 GB a month and says “it’s common for full nodes on high-speed connections to use 200 gigabytes upload or more a month”. To limit uploads, set Max Upload Target in the Bitcoin Node app’s settings (megabytes per 24 hours; 0 means no limit). It is a target rather than a hard cap, and apps on your Umbrel are exempt from it.

Once synced, the node only needs each new block as it is mined, about one every ten minutes.

Step 5: Connect Your Wallet

Your node only protects your privacy once your wallet talks to it. Until then, the wallet asks a public server about your addresses, and that server learns your balance, your history and your IP address.

Most wallets don’t talk to Bitcoin Core directly. They speak the Electrum protocol, so the usual route is an Electrum server: a program that indexes the blockchain by address, so your wallet can ask “what happened to these addresses?” and get an instant answer from your own node.

On a Raspberry Pi, that route is closed for now. umbrelOS 2.0 can move an app to an external drive only if the app is built for it. Bitcoin Node is; as of November 2026, none of the Electrum servers in the App Store (Electrs, Fulcrum and ElectrumX) is (compare the app definitions for Bitcoin Node, Electrs , Fulcrum and ElectrumX). Their index, about 80 GB for Electrs and more for Fulcrum, would fill the 32 GB card that umbrelOS and your other apps run from. So what you do depends on your computer.

On a Raspberry Pi: connect Sparrow straight to Bitcoin Core

Sparrow Wallet, on your computer, can use Bitcoin Core directly, with no Electrum server in between (Sparrow’s guide).

1. Wait until Bitcoin Node shows 100% synced. Until then Sparrow can’t find your transactions.
2. In the Bitcoin Node app, click Connect, choose RPC Details and keep Tor (a private network route, explained below) selected. It shows a .onion address, a port, a user name and a password. Use these Tor details even at home: by default, Umbrel’s Bitcoin Node accepts these connections only from apps on the Umbrel and through Tor, not from other computers on your network.
3. In Sparrow, open Settings, go to the Server tab and choose Bitcoin Core. Enter the .onion address and the port, choose User/Pass, enter the user name and password, and click Test Connection. Sparrow reaches .onion addresses through its own built-in Tor.
4. When you add a wallet, Sparrow asks for the date it was first used. If you’re unsure, pick an earlier date; the first scan just takes longer.

Expect it to be slower than an Electrum server: Sparrow’s guide calls Bitcoin Core over Tor “fairly slow”. Keep the RPC password private, because it gives full control of Bitcoin Core. Bitcoin Core’s documentation also warns that this interface “has not been hardened to withstand arbitrary Internet traffic”, even when reached through “something like a Tor onion service”, so keep the .onion address as private as the password.

On a mini-PC: add an Electrum server

On a mini-PC with a 2 TB internal SSD, umbrelOS keeps every app on that SSD, so an Electrum server fits and there is nothing to move.

1. Install Electrs (smaller index) or Fulcrum (faster, bigger index) from the App Store. Once Bitcoin Core has finished syncing, it builds its index, which can take many hours.
2. Open the app. It shows what to type into your wallet: an address, a port (a number that picks out the right program on the node) and whether to use SSL (an encrypted connection). A switch chooses between Local Network, for use at home, and Tor, a private route for use away from home (both explained below).
3. In Sparrow Wallet, open Settings, go to the Server tab, choose Private Electrum, enter that address and port, and click Test Connection.

Other wallets that accept a private Electrum server, such as BlueWallet and Electrum, connect the same way: find their server or network setting and enter the same details.

Using your node away from home

On a Raspberry Pi, Sparrow already reaches Bitcoin Core over Tor, so it works the same anywhere. With an Electrum server, wallets use the local address at home. Away from home, Umbrel gives you two options (Umbrel’s remote access guide):

• Tailscale, which Umbrel recommends, is an app that links your own devices in a private network without exposing the node to the internet. Your traffic stays encrypted between your devices, but the connection is set up through Tailscale’s company servers.
• Tor is a network that hides who is talking to whom. Choose Tor in Electrs or Fulcrum to get a .onion address that Sparrow can use. It is slower but needs no account. To open the Umbrel dashboard itself over Tor, turn on Settings → Advanced settings → Remote Tor access.

Step 6: Add Lightning (Optional)

Lightning moves bitcoin through channels: a balance shared with one other node, opened with one on-chain transaction and then updated instantly with each payment. On your own node, no company holds your Lightning payments or sees all of them. It also brings new duties, so add it only when Bitcoin Core shows 100% synced.

1. Install Lightning Node from the App Store. It runs LND, the Lightning software most node platforms ship. (Core Lightning is also available; the steps below use LND.)
2. Write down the 24 secret words it gives you, on paper, and store them like any seed. They recover the Lightning node’s on-chain money. On their own, they do not recover money in channels; that also needs the channel backup in Step 7.
3. Fund it: send some bitcoin to the on-chain address the Lightning app shows.
4. Open your first channel to a peer, another node that is online around the clock and well connected. Lesson 4.8 explains how to choose one. The channel works once the opening transaction has a few confirmations, that is, once it is a few blocks deep in the chain.

How big? A channel’s size is the most you can move through it at once, and opening and closing it each cost an on-chain fee. Amounts on Lightning are counted in sats (satoshis, the smallest unit of bitcoin: 100 million sats make one bitcoin). If you want to route other people’s payments, Lesson 4.8 explains why channels under 500,000 sats do little and why 1 to 10 million sats is typical. For a first channel that only pays your own bills, pick an amount you’re comfortable having locked up for months. Some large nodes refuse small channels: LND lets each operator set a minimum size (minchansize in its settings). If yours is below a peer’s minimum, the peer rejects the request before any bitcoin leaves your wallet.

Why your new node can’t receive yet

A channel you fund starts with its whole balance on your side. Open a 1,000,000-sat channel and you can send almost 1,000,000 sats through it, but you can receive nothing, because there is nothing on the other side to move toward you. The capacity to receive is called inbound liquidity, and a new node has none. Pay 300,000 sats for something and those sats now sit on your peer’s side: you can receive almost 300,000 sats through that channel (your peer must keep a small reserve, about 1% of the channel, on its side).

To get inbound liquidity (all covered in Lesson 4.2): spend first; ask another node to open a channel to you; buy one from a Lightning Service Provider, a company that opens channels to you for a fee; or swap part of your channel balance out to an on-chain address (a “Loop Out”).

Lightning on your phone

To spend from your node on the move, install Zeus. In the Lightning Node app, open the three-dot menu at the top and choose Connect wallet: it shows a QR code that connects over Tor by default. In Zeus, choose to connect a remote node and scan it. Treat that QR code like a key: it carries full admin access to LND, so whoever scans it can spend your Lightning node’s funds, its on-chain balance included. Don’t screenshot it or share it.

Step 7: Back Up and Keep It Up to Date

Back up your Lightning channels the safe way

Your 24 words rebuild the on-chain wallet, but not your channels: what each channel holds lives only on the node. LND keeps two very different files about channels:

• The channel database (channel.db) is the live record of every channel. Never restore an old copy or start a node on one: an old copy holds an earlier balance, and publishing one is what Lightning punishes as cheating, so your peer could take the whole channel (LND’s recovery guide). A copy kept aside is not a backup, though a specialist tool such as chantools can extract a fresh channel.backup from it.
• The static channel backup (channel.backup) lists your channels and how to reach each peer. It is always safe to copy, and it is encrypted with a key derived from your 24 words.

What to do: after every channel you open or close, copy a fresh channel.backup somewhere other than the node, such as your computer or a USB stick. On Umbrel, open the Lightning Node app’s three-dot menu and choose Download channel backup file. The app also uploads an encrypted copy to Umbrel’s backup server automatically, a setting that is on by default (Umbrel’s explanation). Keep your own copy anyway: on a Raspberry Pi, the Lightning app lives on the microSD card, the part most likely to fail.

What a restore does: with your 24 words and the channel backup, a new node asks each peer to close its channel, and your settled balance returns to your on-chain wallet; the channels end rather than resume. umbrelOS Backups leave LND’s channel database out (it is listed in the Lightning app’s backup exclusions), so restoring a whole Umbrel never brings back an old, dangerous state. Our lesson on Lightning backups and watchtowers goes through a restore step by step, with what it can’t recover.

Switch on a watchtower if the node may go offline

Your node only catches a peer publishing an old balance while it is running, and on small channels it has about a day to respond (Lesson 4.1 explains why). A watchtower watches for you while the node is off. The Lightning Node app’s watchtower client is off by default (wtclient.active, in its default settings). If your node might ever be off for most of a day or longer, switch it on under Advanced Settings in the Lightning Node app and add a tower when you open your first channel, not the night before a trip: a tower only guards the balances revoked after its client is switched on. Lesson 4.8 gives the steps, and Lesson 4.9 explains where to run a tower and how to check it is working.

Install updates yourself

Nothing on Umbrel updates on its own: umbrelOS updates “are never installed automatically” (Umbrel), and apps don’t update themselves either (Umbrel). You decide when.

• umbrelOS: Settings → Software update → Check for update, read the release notes, then Install now. Don’t turn the Pi off while it installs.
• Apps (Bitcoin Node, Lightning Node, and Electrs or Fulcrum if you use one): open the App Store and click Updates in the top-right corner.

Check at least once a month, and look at our security advisories. In November 2026 one applies to this setup: Lightning nodes on Linux should run umbrelOS 2.0.1 or later and Lightning Node 0.21.6 or later. Node platforms often ship a new Bitcoin Core version a little after its release, once they have tested it; that is normal.

Watch disk space and power

Check the SSD’s free space now and then. When it runs low, move to a bigger SSD rather than pruning, which would stop an Electrum server and keep Sparrow from scanning older blocks. A small UPS, a battery that keeps the node running through short power cuts, protects the card and the databases.

When Something Goes Wrong

umbrel.local won’t open

• Give the first start a few more minutes.
• Use the IP address from your router’s list of connected devices, for example http://192.168.1.45.
• Check that the Ethernet cable is firmly in at both ends and the link lights are on.
• If the Pi never starts, write the card again. An outdated bootloader is a common cause on a Pi 4 and can happen on early Pi 5 boards (Step 1).
• Try another browser or device; some networks don’t resolve .local names.

The sync is very slow or stuck

• Make sure Bitcoin Node is on the SSD (Step 3), not on the card or a hard drive.
• Check the power supply: on a Pi 5, a supply that can’t deliver 5 A limits the USB devices, the SSD included, to 600 mA.
• Check the temperature and your internet connection.

Random restarts or a corrupted card

• Use the official power supply, and consider a UPS.
• If the card is corrupted, you may have to write it again. Your blocks live on the SSD, but your other apps, Lightning included, live on the card. This is when your umbrelOS backup and your copy of channel.backup matter.

Lightning channels won’t open, or keep closing

• Wait until Bitcoin Core shows 100% synced.
• Check that your channel is above the peer’s minimum size.
• Keep the node online. Long downtime can lead a peer to force-close your channel, closing it alone on-chain, which costs fees.

Frequently Asked Questions

Should I buy a pre-built node or build my own?

Pre-built nodes such as Umbrel’s Umbrel Home^[#aff] (from $499) and Start9’s Server One (from $899; both prices checked 8 November 2026) offer convenience — everything arrives assembled and pre-configured. Building your own takes 30 to 60 minutes of hands-on work and teaches you how your node fits together; compare current board and SSD prices before deciding, since memory costs pushed Raspberry Pi prices up during 2026. For most readers, building your own is straightforward. Pre-built makes sense if you want plug-and-play.

Is a Raspberry Pi 4 still good enough?

For learning, yes; for a node that holds Lightning money, Umbrel says no. Its Raspberry Pi guide recommends the Pi 5 because it “works well with USB drives, which can make a Pi 4 crash”, and calls the Pi 4 “fine for tinkering, or if you already have one”. This setup keeps the blocks on a USB SSD, and sudden crashes are the last thing you want on a machine with open Lightning channels. A Pi 4 also syncs more slowly, and many boards need a bootloader update before umbrelOS 2.0 will start. If you already have one, use it to learn, then move to a Pi 5 or a mini-PC before you put channel money on it. (StartOS supports only the Pi 4 among Raspberry Pis, so StartOS users who want the same reliability should choose a mini-PC.) More in our guide to running your own Bitcoin node.

Can I use an old computer instead?

Yes. umbrelOS and StartOS both run on ordinary Intel and AMD PCs, and Bitcoin Core runs on Windows, macOS and Linux without any platform. You still want about 2 TB of SSD space. The trade-off is uptime: Lightning needs the machine on around the clock.

What if my internet has a data cap?

The first sync downloads about 800 GB. After that, expect about 20 GB a month of downloads and possibly 200 GB or more of uploads, which you can limit with Max Upload Target. Pruning won’t shrink that first download, because a pruned node still downloads every block once. It does cut uploads, since a pruned node stops sharing old blocks with other nodes, but it also stops Electrs and Fulcrum from working; Max Upload Target limits uploads without that cost. Some people do the first sync on an unlimited connection, at a friend’s place or at work, then bring the node home.

Check Your Understanding

1. A friend suggests a 1 TB drive with pruning switched on to save money. Why does this lesson say to buy 2 TB instead?

Answer

Bitcoin Core already plans for about 900 GB of disk (the blocks plus the data it keeps alongside them), and that grows about 90 GB a year. On Umbrel, the transaction and block-filter indexes it builds by default add tens of gigabytes more, so a 1 TB drive is already too small, before any Electrum server. Pruning would solve the space problem but break Electrs and Fulcrum, which most wallets need to use your node, and stop a wallet connected straight to Bitcoin Core, like Sparrow, from scanning older blocks. It wouldn’t save any download either, and turning it off later means downloading the whole blockchain again.

2. You opened a 1,000,000-sat channel yesterday. Today a friend tries to pay you 50,000 sats over Lightning and it fails. Why, and what can you do?

Answer

All of the channel’s balance is on your side, so you have no inbound liquidity: there is nothing on the other side that can move toward you. Spend some sats first, ask another node to open a channel to you, buy inbound liquidity from a Lightning Service Provider, or swap part of your balance out on-chain. Each of these puts sats on the far side of a channel.

3. The microSD card in your Umbrel dies with Lightning channels open. What do you need to get the money back, and what must you never do?

Answer

You need your 24 Lightning words and a recent copy of channel.backup kept off the node (or Umbrel’s automatic encrypted copy). With them, a new node asks each peer to close its channel, and your settled balance returns on-chain. Never restore an old copy of channel.db: it holds an earlier balance, and publishing it lets your peer take the whole channel as a penalty.

Practical guides

• Run a Bitcoin Node: Full Setup Guide
• Bitcoin Node Connectivity: Troubleshooting