LND Mempool Fee Estimation Failed -- Fix CPFP and RBF

Problem

LND fails to estimate mempool fees, transactions get stuck, or CPFP/RBF does not trigger correctly.

Check Fee Estimator Status

lncli feereport

Configure Fee Estimator in lnd.conf

[fee]
url=https://mempool.space/api/v1/fees/recommended

# Or use bitcoind
[bitcoind]
estimatemode=ECONOMICAL

Manual Fee Override for Stuck Txs

# Bump fee via CPFP
lncli wallet bumpfee --sat_per_vbyte 20 <outpoint>

# Or set target conf blocks
lncli wallet bumpfee --target_conf 2 <outpoint>

Check Pending Sweeps

lncli wallet pendingsweeps

Common Issues

- "fee estimation failed" — bitcoind not synced, or mempool.space URL unreachable

- CPFP not triggering — anchor output too small; ensure anchor reserve is funded

- RBF rejected — original tx not signaling RBF (sequence < 0xFFFFFFFE)

Best Practice

Use mempool.space fee API for accurate real-time estimates. Keep at least 50,000 sats on-chain as anchor reserve for CPFP. Monitor with lncli wallet pendingsweeps regularly.