Panic error while attempting connect to peer

[bosi95]

Context

bee v2.8.1

Summary

After upgrading to the latest bee version v2.8.1 and restarting the node causes the node to crash with a panic error while attempting to connect to a peer.

Expected behavior

After the upgrade the node shall be able to connect to peers and gracefully handle connection errors.

Actual behavior

The node exits with a panic error with the following logs:
"time"="2026-07-08 08:44:10.117525" "level"="debug" "logger"="node/kademlia" "msg"="attempting connect to peer" "peer_address"="a689bea26fd351944906fe09b6a48aaf38ed069150ccf3211a0fdbcb0c4572f3"
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x153a5ee]

goroutine 221926735 [running]:
github.com/ethersphere/bee/v2/pkg/topology/kademlia.(*Kad).connectionAttemptsHandler.func1(0x3748b5b73960)
github.com/ethersphere/bee/v2/pkg/topology/kademlia/kademlia.go:431 +0x1ee
github.com/ethersphere/bee/v2/pkg/topology/kademlia.(*Kad).connectionAttemptsHandler.func2(0x3748bbf0e070)
github.com/ethersphere/bee/v2/pkg/topology/kademlia/kademlia.go:492 +0x28d
created by github.com/ethersphere/bee/v2/pkg/topology/kademlia.(*Kad).connectionAttemptsHandler in goroutine 221925879
github.com/ethersphere/bee/v2/pkg/topology/kademlia/kademlia.go:503 +0x1a9
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x153a5ee]

goroutine 221926737 [running]:
github.com/ethersphere/bee/v2/pkg/topology/kademlia.(*Kad).connectionAttemptsHandler.func1(0x3748b5b739e0)
github.com/ethersphere/bee/v2/pkg/topology/kademlia/kademlia.go:431 +0x1ee
github.com/ethersphere/bee/v2/pkg/topology/kademlia.(*Kad).connectionAttemptsHandler.func2(0x3748bbf0e070)
github.com/ethersphere/bee/v2/pkg/topology/kademlia/kademlia.go:492 +0x28d
created by github.com/ethersphere/bee/v2/pkg/topology/kademlia.(*Kad).connectionAttemptsHandler in goroutine 221925879
github.com/ethersphere/bee/v2/pkg/topology/kademlia/kademlia.go:503 +0x1a9

Steps to reproduce

1. Stop and upgrade a node from v2.8.0 to v2.8.1
2. Restart the node and wait until it tries to connect to peers
3. The node exits with a panic error after some time

Possible solution

Only a workaround: nuking the db and then restarting the node solves the problem.

AI Disclosure

• This issue contains suggestions and text generated by an LLM.
• I have reviewed the AI generated content thoroughly.
• I possess the technical expertise to responsibly review the AI generated content mentioned in this issue.

[akrem-chabchoub]

@bosi95 Thanks for raising the issue.

Could you please share the config.yaml that you are using ?
Because I retried the scenario you mentioned but couldn't reproduce it.

I even went from 2.7 to 2.8.1 and didn't face the issue.

[akrem-chabchoub]

@bosi95 The issue does not appear to be directly related to the upgrade; instead, it is likely caused by some corrupted or modified legacy data. I wasn't able to reproduce the bug locally despite testing all scenarios, which further suggests it might be an isolated data issue.

I've submitted a fix for this in #5534.