Invalid expression

Terraform
1

Error: Invalid expression
│
│ on main.tf line 22, in resource “aws_instance” “app_server”:
│ 22: + Name = var.instance_name
│
│ Expected the start of an expression, but found an invalid expression token.

2

It’s hard to tell without the full resource definition, but it seems like you’re trying to set the instance name. This is done via setting the tag Name:

resource "aws_instance" "web" {
  .
  .
  tags = {
    Name = var.instance_name
  }
}
3

I think that + symbol before Name is probably what this error is reporting, since a plus sign is not valid in that position.

If you copied the terraform plan description of some changes into your configuration then note that terraform plan is only configuration-language-like for ease of human reading and is not intended to be copied verbatim into a .tf file to run. At the very least you’ll need to remove the +, -, ~ and other such markers that Terraform uses to describe what’ll be changed by a particular action.