Parse Go Nil Pointer Dereference Stack Trace

Understanding Go Nil Pointer Dereference Panics

A nil pointer dereference is the Go equivalent of a NullPointerException in Java or TypeError in JavaScript. It occurs when code attempts to access a method or field on a nil pointer value.

Stack Trace Example

goroutine 1 [running]:
runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x18 pc=0x497a23]

goroutine 1 [running]:
main.(*UserService).GetProfile(0x0, {0xc000014060, 0x24})
        /app/services/user.go:42 +0x23
main.handleGetUser({0x7f3c28, 0xc000090000}, 0xc000088000)
        /app/routes/user.go:18 +0x8f

Signal Information

Go nil pointer panics include OS-level signal information:

• SIGSEGV --- segmentation violation (most common for nil dereferences)
• code=0x1 --- the signal code from the OS
• addr=0x18 --- the memory address that was accessed (low addresses like 0x0-0x100 typically indicate nil + field offset)
• pc=0x... --- the program counter where the fault occurred

Identifying the Nil Receiver

When a method is called on a nil pointer, the receiver argument shows 0x0:

main.(*UserService).GetProfile(0x0, ...)

The 0x0 as the first argument indicates that the *UserService receiver is nil. This immediately tells you that GetProfile was called on a nil *UserService pointer.

Common Causes

• Returning nil from a constructor or factory function without checking
• Not checking error return values that indicate a nil result
• Interface values that are nil
• Uninitialized struct pointer fields
• Race conditions where one goroutine nils a pointer that another is using

Prevention

• Always check for nil before dereferencing pointers
• Use the if err != nil pattern consistently
• Initialize struct fields in constructors
• Use race detector (go run -race) during testing