Scanning for missed UTXOs causes crash an CLN won't boot anymore SIGNAL 11

[Schnema1]

Errror

With debug enabled:
INFO lightningd: Scanning for missed UTXOs from block 908329
.....
DEBUG lightningd: Adding block 921174: 00000000000000000000a8e0eefb0f6e3ed9ca0bb64fa97aecc9c65c64a91718
DEBUG plugin-bcli: Log pruned 593 entries (mem 10528925 -> 6954560)
DEBUG plugin-bcli: Log pruned 264 entries (mem 10496687 -> 4148574)
BROKEN lightningd: FATAL SIGNAL 11 (version v25.12.1)
BROKEN lightningd: backtrace: common/daemon.c:46 (send_backtrace) 0x55e79c2c1497
BROKEN lightningd: backtrace: common/daemon.c:83 (crashdump) 0x55e79c2c14e6
BROKEN lightningd: backtrace: (null):0 ((null)) 0x7f170682d51f
BROKEN lightningd: backtrace: bitcoin/block.c:213 (bitcoin_block_from_hex) 0x55e79c2ebfea
BROKEN lightningd: backtrace: lightningd/bitcoind.c:496 (getrawblockbyheight_callback) 0x55e79c20ffd7
BROKEN lightningd: backtrace: lightningd/plugin.c:701 (plugin_response_handle) 0x55e79c263bc6
BROKEN lightningd: backtrace: lightningd/plugin.c:790 (plugin_read_json) 0x55e79c269175
BROKEN lightningd: backtrace: ccan/ccan/io/io.c:60 (next_plan) 0x55e79c2fbed9
BROKEN lightningd: backtrace: ccan/ccan/io/io.c:422 (do_plan) 0x55e79c2fc3b8
BROKEN lightningd: backtrace: ccan/ccan/io/io.c:439 (io_ready) 0x55e79c2fc475
BROKEN lightningd: backtrace: ccan/ccan/io/poll.c:470 (io_loop) 0x55e79c2fdf14
BROKEN lightningd: backtrace: lightningd/io_loop_with_timers.c:22 (io_loop_with_timers) 0x55e79c237f87
BROKEN lightningd: backtrace: lightningd/lightningd.c:1495 (main) 0x55e79c23daec
BROKEN lightningd: backtrace: (null):0 ((null)) 0x7f1706814d8f
BROKEN lightningd: backtrace: (null):0 ((null)) 0x7f1706814e3f
BROKEN lightningd: backtrace: (null):0 ((null)) 0x55e79c20dd64
BROKEN lightningd: backtrace: (null):0 ((null)) 0xffffffffffffffff

Comming from v25.09 what I did:
I did clone my old systemdisc with clonezilla. The node booted an ran like before.

• So I did upgrade CLN to 25.12 too, but kept Bitcoin Core v29 for some hours.
• If I remember correct, the CLN started without issue.
• I then changed the config file and added autoclean options. Following the docs.
• But the next day I discovered dozends of crash logs, and CLN fails to load.

What I have tried so far:

• Upgrade CLN to 25.12.1 > same error
• Bitcoin Core to v30.2 and back to v29 did not help
• Delete the gossip store > still same

My "not developer" analysis:
Parsing the long log files, to me it seems cln rescans for missed UTXO. But apparently the bcli plugin fails because.... well, that seems to be the magical question.
First off it checks a 5 month old block. Why? I don't know as the node was offline maybe 12hours.

Could maybe autoclean have cleaned some entries which sould not have be cleaned just yet?
Can I avoid this missed UTXO check or set it to a blockheight few days ago?
How can get back online?
More detaild logs can be provided if you tell me how and what.

EDIT
The block can be loaded if called bitcoin-cli getblock
Bitcoin Core is not pruned

[cdecker]

Thank you for the detailed report, let's try to collect some more information: by enabling --log-level=debug you can enable the logging of messages, including the block that is causing the crash (hex encoded). And then we can disambiguate better.

For reference: there are multiple blocks in play here:

• Blocks between 908329 and the current sync height, looking for UTXOs that might have been channels.
• Block 921174 which is the current sync head, and it is attempting to add it to its view of the blockchain.

I'm guessing it is the latter, seeing the proximity of the crash to the log announcing the block being added, but better be sure, before getting lost in the wrong side of the system :-)

[Schnema1]

Thanks! Here the =debug logfile. The =Io is >20MB. Shall I upload it too?

cln.log

Is this the part?

cat error032026.log | grep -B1 block

2026-03-24T10:08:30.834Z plugin-bcli: [IN] 7b226a736f6e727063223a22322e30222c226964223a22636c6e3a657374696d61746566656573233238222c22726573756c74223a7b226665657261746573223a5b7b22626c6f636b73223a322c2266656572617465223a313132327d2c7b22626c6f636b73223a362c2266656572617465223a313030307d2c7b22626c6f636b73223a31322c2266656572617465223a313030307d2c7b22626c6f636b73223a3130302c2266656572617465223a313030307d5d2c22666565726174655f666c6f6f72223a313030307d7d0a0a
2026-03-24T10:08:30.834Z lightningd: "cln:getrawblockbyheight#29"[OUT] 
--
2026-03-24T10:08:31.298Z plugin-bcli: [IN] 303731.........BLOCK DATA........83230376431396430393965

2026-03-24T10:08:36.510Z DEBUG   lightningd: Adding block 921160: 000000000000000000016529a5a9a7429a791ced92d33b25c0738bd876521f77
2026-03-24T10:08:36.590Z lightningd: "cln:getrawblockbyheight#61"[OUT] 
--
2026-03-24T10:08:37.461Z **BROKEN** lightningd: backtrace: (null):0 ((null)) 0x7efd21b2a51f
2026-03-24T10:08:37.461Z **BROKEN** lightningd: backtrace: bitcoin/block.c:213 (bitcoin_block_from_hex) 0x5654c04adfea
2026-03-24T10:08:37.461Z **BROKEN** lightningd: backtrace: lightningd/bitcoind.c:496 (getrawblockbyheight_callback) 0x5654c03d1fd7