downloader.go: findAncestor invalid memory address or nil pointer dereference (known, but nil header)

[zhangsj]

Version: 1.11.5-stable update to v1.11.14
old version Version: 1.11.5-stable
new version CoreGeth/v1.11.14-stable-b711e954/linux-amd64/go1.15.2
ubuntu 16.04

command
geth --classic --datadir /opt/etc -rpcvhosts * --rpcaddr 0.0.0.0 --rpcaddr 0.0.0.0 --rpc --http --http.api eth,net,web3,txpool

[iquidus]

Unrelated to the nil pointer dereference, but your flags are duplicating. --http and --rpc do the same thing (--rpc is deprecated, replaced by http)

geth --classic --datadir /opt/etc -rpcvhosts * --rpcaddr 0.0.0.0 --rpcaddr 0.0.0.0 --rpc --http --http.api eth,net,web3,txpool

should be

geth --classic --datadir /opt/etc --http  --http.vhosts * --http.addr 0.0.0.0 --http.api eth,net,web3,txpool

[zhangsj]

can not fix

[meowsbits]

Hm, interesting. Thanks for your report.

This looks like a known/reported error at upstream:

• Panic on "Looking for peers" ethereum/go-ethereum#21496
• SEGV on corrupt leveldb due to assumption of existence of headers.  ethereum/go-ethereum#21421
• geth repeatedly crashes with SIGSEGV ethereum/go-ethereum#20190
• Panic in findAncestor ethereum/go-ethereum#18994
• panic: runtime error: invalid memory address or nil pointer dereference ethereum/go-ethereum#18388 (comment)
• geth panics while syncing: invalid memory address or nil pointer dereference ethereum/go-ethereum#19305

Please see Peter's comment at: ethereum/go-ethereum#21496 (comment) for instructions toward recovery (noting that you'll want to replace the block number with one pertinent to your situation).

Also, if you're able and willing help us out with debugging (before attempting to fix), it would be great to see logs if you run --vmodule=downloader=5 so we can see exactly which blocks are causing the issue, and if possible, to upload your chaindata directory somewhere so we can examine it.

Just for reference, here's the flow causing the error at ethereum/go-ethereum (same logic) - https://github.com/ethereum/go-ethereum/blob/master/eth/downloader/downloader.go#L936

[meowsbits]

Getting reports that this has been reproduced by a couple of others with upgrade to v1.11.15