What Is a Nil Pointer in Go

A nil pointer in Go is a pointer variable that holds no memory address, representing the absence of a value. In Go 1.21 and later, calling panic(nil) triggers a runtime error by default unless you explicitly restore the old behavior using the panicnil GODEBUG setting. To allow panic(nil) again, set the environment variable or use a directive in your source file:

export GODEBUG=panicnil=1

Alternatively, add this directive to the top of your Go source file:

//go:debug panicnil=1

A nil pointer is like a variable that points to nothing, similar to an empty address on a map. In newer versions of Go, trying to crash your program using this empty address is blocked by default to prevent bugs. You can turn this safety feature off if you have old code that relies on it.