LND Anchor Output Errors - Fix CPFP and Fee Bumping Issues

What Are LND Anchor Output Errors?

Anchor outputs reserve a small amount of sats (330 sat) in each channel commitment to allow fee bumping via CPFP. Errors occur when the wallet lacks funds for fee bumping or anchor scripts are misconfigured.

Common Errors

• insufficient funds to bump fee for anchor output
• anchor_reserved_value: wallet balance too low
• cannot sweep anchor: no confirmed utxo available
• force close stuck: anchor CPFP failed

Root Causes

• On-chain wallet has < 10,000 sat confirmed balance
• All UTXOs are unconfirmed or locked
• Node using anchors but no on-chain funds reserved
• High mempool fees drain anchor reserves quickly

Fix: Keep Wallet Funded

# Check on-chain wallet balance
lncli walletbalance

# Recommended: keep >= 100,000 sat on-chain
# for anchor fee bumping across multiple channels

# Deposit to your LND wallet address
lncli newaddress p2tr

Fix: Check Anchor Type

# Verify channel uses anchors
lncli listchannels | python3 -c "
import json,sys
for c in json.load(sys.stdin)['channels']:
  print(c['chan_id'], c.get('commitment_type','unknown'))
"

# anchors = commitment_type: ANCHORS or SCRIPT_ENFORCED_LEASE

Fix: Force-Close with Fee Bump

# If anchor sweep is stuck, bump manually
lncli wallet bumpfee --sat_per_vbyte 50 <anchor_outpoint>

# List pending sweeps
lncli pendingchannels

Prevention

• Always maintain >= 50k sat on-chain when running anchor channels
• Monitor walletbalance in Prometheus/Grafana alerts
• Use --max_local_csv flag to control CSV delay on force close

Running into anchor issues on your node? DM on Nostr for help.