panic: runtime error: invalid memory address or nil pointer dereference when running Blockchainr

Question

I run blockchainr and get the following terminal output:

17:39:57 2015-06-16 [INF] loading db leveldb
panic: runtime error: invalid memory address or nil pointer dereference
    panic: runtime error: invalid memory address or nil pointer dereference
[signal 0xb code=0x1 addr=0x0 pc=0x402cb63]

goroutine 1 [running]:
main.search(0x4911ef8, 0xc20806e2d0, 0x0, 0x0, 0x4911ef8)
    /Users/mesquka/Downloads/blockchainr-master/src/blockchainr/main.go:185 +0x3fa
main.main()
    /Users/mesquka/Downloads/blockchainr-master/src/blockchainr/main.go:284 +0x3ce

goroutine 5 [semacquire]:
sync.(*Cond).Wait(0xc208045100)
    /usr/local/go/src/sync/cond.go:62 +0x9e
github.com/conformal/seelog.(*asyncLoopLogger).processItem(0xc20802c4e0, 0x0)
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_asynclooplogger.go:50 +0xc2
github.com/conformal/seelog.(*asyncLoopLogger).processQueue(0xc20802c4e0)
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_asynclooplogger.go:63 +0x31
created by github.com/conformal/seelog.newAsyncLoopLogger
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_asynclooplogger.go:40 +0x8e

goroutine 6 [semacquire]:
sync.(*Cond).Wait(0xc2080452c0)
    /usr/local/go/src/sync/cond.go:62 +0x9e
github.com/conformal/seelog.(*asyncLoopLogger).processItem(0xc20802c5a0, 0x0)
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_asynclooplogger.go:50 +0xc2
github.com/conformal/seelog.(*asyncLoopLogger).processQueue(0xc20802c5a0)
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_asynclooplogger.go:63 +0x31
created by github.com/conformal/seelog.newAsyncLoopLogger
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_asynclooplogger.go:40 +0x8e

goroutine 7 [syscall]:
os/signal.loop()
    /usr/local/go/src/os/signal/signal_unix.go:21 +0x1f
created by os/signal.init·1
    /usr/local/go/src/os/signal/signal_unix.go:27 +0x35

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
    /usr/local/go/src/runtime/asm_amd64.s:2232 +0x1

goroutine 8 [chan receive]:
github.com/conformal/seelog.(*asyncAdaptiveLogger).processQueue(0xc208010150)
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_adaptivelogger.go:127 +0x89
created by github.com/conformal/seelog.newAsyncAdaptiveLogger
    /Users/mesquka/Downloads/blockchainr-master/src/github.com/conformal/seelog/behavior_adaptivelogger.go:84 +0x6ba

I am running on OSX Yosemite 10.10.3 with go version go1.4.2 darwin/amd64

The code is at https://github.com/FiloSottile/blockchainr

The specific commands I've run (in order) are:

• make all
• ./bin/btcd --datadir=~/Btcd/
• ./bin/blockchainr -datadir ~/Btcd/

The last command is where I get this terminal output.

Answer 1

Your problem lies with Blockchainr main.go following lines:

var (
    dataDir = flag.String("datadir", filepath.Join(btcutil.AppDataDir("btcd", false), "data"), "BTCD: Data directory")
    dbType  = flag.String("dbtype", "leveldb", "BTCD: Database backend")
)

As you can see, if you don't specify a dbtype flag it defaults to "leveldb" so it expects the datadir param to contains the path to a LevelDB database.