Unable to fully sync neutrino (with validatechannels=true). Config included

[humberroll29]

Hello,
My issue is the inability to correctly sync LND with the neutrino backend and validatechannels=true. As far as i understand, this is required to get channel balances and channel points to be populated in your graph, otherwise they are "0". I let the daemon run and it seems to download a bunch of cfilters and some blocks, but the graph is nowhere near full.

getinfo returns :
"synced_to_chain": true
"synced_to_graph": false

it remains this way after many hours with seemingly no progress. I'm unable to get any responses for getnodeinfo and getchaninfo

If i simply set validatechannels=false (or comment it out altogether), i quickly get synced up with both graph/chain and i can easily do getnodeinfo and getchaninfo on any node/channel. The only issue is like i mentioned before, i want capacity and chanpoints to be populated in the graph, which i have failed to accomplish.

I have attempted many different configurations in the past, have tried v 0.18.5 and 0.19.2, here is present config:

[Application Options]
debuglevel=info,BTCN=debug,LNWL=trace,GRPH=debug
connectiontimeout=60s
http-header-timeout=10s
maxpendingchannels=5
listen=localhost
tlsautorefresh=true
tlsdisableautofill=true
bitcoin.basefee=2000
bitcoin.feerate=2
minchansize=200000
autopilot.minchansize=4
accept-keysend=true
coop-close-target-confs=30
wtclient.active=false
gc-canceled-invoices-on-startup=true
gc-canceled-invoices-on-the-fly=true
numgraphsyncpeers=100


[fee]
fee.url=https://nodes.lightning.computer/fees/v1/btc-fee-estimates.json



[bolt]
db.bolt.auto-compact=true
db.bolt.auto-compact-min-age=168h


[Bitcoin]
bitcoin.active=true
bitcoin.mainnet=true
bitcoin.node=neutrino


[neutrino]

neutrino.maxpeers=20
#neutrino.persistfilters=true
neutrino.validatechannels=true


[rpcmiddleware]

rpcmiddleware.intercepttimeout=5s


[gossip]

gossip.msg-rate-bytes=1024000
gossip.msg-burst-bytes=2048000

Appreciate any help.

[guggero]

This is the expected behavior, and the whole reason why validatechannels=false is the default for Neutrino.
Validating a channel (and fetching its balance) means looking up the transaction in the chain. Because Neutrino doesn't have all blocks, it will request each block from its peers. And that just takes a very long time.

[humberroll29]

This is the expected behavior, and the whole reason why validatechannels=false is the default for Neutrino. Validating a channel (and fetching its balance) means looking up the transaction in the chain. Because Neutrino doesn't have all blocks, it will request each block from its peers. And that just takes a very long time.

@guggero I appreciate the response,

However this doesn't explain why LND just sits and practically does nothing after some time, it basically just sits there and sends/receives pings/pongs without any activity, occasionally getting the latest cfilter/block as it comes in. I have attempted to run getnodeinfo against some "new" nodes and channels (according to 1ML) and it doesn't even find them. Shouldn't LND be frantically trying to get caught up? It requires a restart to get it to show some activity.

[humberroll29]

Here's a short sample of the logs.

2025-08-11 13:01:41.304 [DBG] BTCN: Received ping from ...............:8333 (outbound)
2025-08-11 13:01:41.304 [DBG] BTCN: Sending pong to ...............:8333 (outbound)
2025-08-11 13:01:42.003 [DBG] BTCN: Sending ping to ...............:8333 (outbound)
2025-08-11 13:01:42.030 [DBG] BTCN: Received pong from ...............:8333 (outbound)
2025-08-11 13:01:43.982 [DBG] BTCN: Received ping from ...............:8333 (outbound)
2025-08-11 13:01:43.982 [DBG] BTCN: Sending pong to ...............:8333 (outbound)
2025-08-11 13:01:47.691 [DBG] BTCN: Sending ping to ...............:8333 (outbound)
2025-08-11 13:01:47.711 [DBG] BTCN: Received ping from ...............:8333 (outbound)
2025-08-11 13:01:47.711 [DBG] BTCN: Sending pong to ...............:8333 (outbound)
2025-08-11 13:01:47.712 [DBG] BTCN: Received pong from ...............:8333 (outbound)
2025-08-11 13:01:47.958 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from ...............:8333 (outbound)
2025-08-11 13:01:47.959 [DBG] BTCN: Sending getheaders (locator 00000000000000000001651fd196f1e2fe0aa28a355150dc2b8c00785e3762c5, stop 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:47.992 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from ...............:8333 (outbound)
2025-08-11 13:01:48.009 [DBG] BTCN: Received headers (num 1) from ...............:8333 (outbound)
2025-08-11 13:01:48.009 [INF] BTCN: Processed 1 block in the last 1m52.58s (height 909566, 2025-08-11 13:01:44 +0000 UTC)
2025-08-11 13:01:48.019 [INF] BTCN: Attempting to fetch set of un-checkpointed filters at height=909566, hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to [...............]:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:48.020 [DBG] BTCN: Sending getcfheaders (start_height=909566, stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to [...............]:8333 (outbound)
2025-08-11 13:01:48.068 [DBG] BTCN: Received cfheaders (stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b, num_filter_hashes=1) from ...............:8333 (outbound)
2025-08-11 13:01:48.070 [DBG] BTCN: Received cfheaders (stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b, num_filter_hashes=1) from ...............:8333 (outbound)
2025-08-11 13:01:48.076 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from [...............]:8333 (outbound)
2025-08-11 13:01:48.088 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from ...............:8333 (outbound)
2025-08-11 13:01:48.130 [DBG] BTCN: Received cfheaders (stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b, num_filter_hashes=1) from [...............]:8333 (outbound)
2025-08-11 13:01:48.298 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from ...............:8333 (outbound)
2025-08-11 13:01:48.438 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from ...............:8333 (outbound)
2025-08-11 13:01:48.906 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from [...............]:8333 (outbound)
2025-08-11 13:01:48.995 [DBG] BTCN: Received cfheaders (stop_hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b, num_filter_hashes=1) from ...............:8333 (outbound)
2025-08-11 13:01:49.013 [DBG] BTCN: Received inv (block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) from ...............:8333 (outbound)
2025-08-11 13:01:58.020 [DBG] BTCN: Writing filter headers up to height=909566, hash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b, new_tip=55081d8f52d1303068b561678ab6a6a5ec0f280dcd017ae9465fb140e1a6adf5
2025-08-11 13:01:58.033 [INF] BTCN: Verified 1 filter header in the last 1m52.58s (height 909566, 2025-08-11 13:01:44 +0000 UTC)
2025-08-11 13:01:58.034 [DBG] BTCN: Fetching filters for heights=[909566, 909566], stophash=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b
2025-08-11 13:01:58.034 [DBG] BTCN: Sending getcfilters to ...............:8333 (outbound)
2025-08-11 13:01:58.077 [DBG] BTCN: Received cfilter from ...............:8333 (outbound)
2025-08-11 13:01:58.078 [DBG] BTCN: Sending getdata (witness block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b) to ...............:8333 (outbound)
2025-08-11 13:01:58.083 [INF] GRPH: Pruning channel graph using block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b (height=909566)
2025-08-11 13:01:58.092 [INF] GRPH: Block 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b (height=909566) closed 0 channels
2025-08-11 13:01:58.237 [DBG] BTCN: Received block (hash 0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b, ver 606093312, 2466 tx, 2025-08-11 13:01:44 +0000 UTC) from ...............:8333 (outbound)
2025-08-11 13:01:58.267 [INF] NTFN: New block: height=909566, sha=0000000000000000000130b35c8a4abb50749d9aa7e43d10f7a4589a0fbdf98b
2025-08-11 13:01:58.267 [INF] LNWL: Web API returning 2000 sat/kvb for min relay feerate
2025-08-11 13:02:37.318 [DBG] BTCN: Sending ping to [...............]:8333 (outbound)
2025-08-11 13:02:37.428 [DBG] BTCN: Received pong from [...............]:8333 (outbound)
2025-08-11 13:02:40.372 [DBG] BTCN: Received ping from [...............]:8333 (outbound)
2025-08-11 13:02:40.372 [DBG] BTCN: Sending pong to [...............]:8333 (outbound)
2025-08-11 13:03:03.226 [DBG] BTCN: Sending ping to ...............:8333 (outbound)
2025-08-11 13:03:03.276 [DBG] BTCN: Received pong from ...............:8333 (outbound)
2025-08-11 13:03:03.439 [DBG] BTCN: Received ping from ...............:8333 (outbound)
2025-08-11 13:03:03.439 [DBG] BTCN: Sending pong to ...............:8333 (outbound)
2025-08-11 13:03:03.447 [DBG] BTCN: Sending ping to ...............:8333 (outbound)

[guggero]

Hmm, okay, if there is absolutely no movement at all (and you have BTCN set to debug, which is what I would've suggested), then perhaps there is a lock somewhere. Could you provide both a goroutine dump as well as a CPU profile please? https://github.com/lightningnetwork/lnd/blob/master/docs/debugging_lnd.md#different-types-of-profiles

[humberroll29]

I have also attempted a workaround where i spun up another LND instance on the same network, this time with validatechannels=false and attempted to add it as a gossip.pinned-sycners to see if i can sync my other LND's graph with this one.
The logs show :
peer has bypassed ban threshold and
gossiper has banned remote's key

over and over, i'm only able to sync for several seconds before those messages keep showing up. Couldn't find a way to unban or disable banning alltogether. Very stuck.

[djkazic]

There's a known issue where neutrino-backed LND nodes will send bad gossip data back, causing the sender to be banned.

[mohamedawnallah]

With this PR (#10280), it will solve that issue. cc @saubyk we can safely resolve that discussion