runtime error: invalid memory address or nil pointer dereference Golang

Edwin Siby
2 min readJun 13, 2023

The most common runtime error in go. can be solved easily.

her the error is in prop.go file at line 89. Like this, you can easily find the error point
  1. Uninitialized Pointer: If you declare a pointer variable without assigning it a value, it will be nil by default. Attempting to dereference such a pointer will result in the mentioned error. To fix this, initialize the pointer using the new() function or by assigning it a valid memory address.

Example:

var ptr *int               // Uninitialized pointer
value := 42
ptr = &value // Initializing pointer with a valid memory address

2.

Nil Pointer: If you explicitly assign nil to a pointer and then try to dereference it, you’ll encounter the same error. Ensure that your pointer is assigned a valid memory address before using it.

Example:

var ptr *int = nil        // Assigning nil to pointer
value := 42
ptr = &value // Assigning a valid memory address to the pointer

3.

Missing Error Handling: Functions in Go can return nil pointers when an error occurs. If you don’t check the returned value for nil before accessing it, you’ll encounter a nil pointer dereference error. Always handle the error condition appropriately.

Example:

func fetchData() (*Data, error) {
// ...
}

data, err := fetchData()
if err != nil {
// Handle the error
}
// Use the data pointer only if it's not nil

4.

Slices and Maps: If you’re working with slices or maps, a common cause of this error is accessing an element using an invalid index or key. Make sure the index/key is within the bounds of the slice or map before accessing it.

Example:

var mySlice []int
// ...
element := mySlice[5] // Make sure the index is within the valid range
var myMap map[string]int
// ...
value := myMap["key"] // Ensure "key" exists in the map before accessing it

Carefully review your code and check for uninitialized or nil pointers. Ensure that pointers are assigned valid memory addresses before dereferencing them. Also, double-check your error handling to prevent using nil pointers returned by functions.

Have a nice day Gophers.

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