Workaround for application insights instances created using Terraform AzureRM provider v1.x when upgrading to v2.0

application-insights.tf

# The application_type attribute is now case senstive. If the resource has been previously created with provider v1.x and the 
# application_type was not lower case, then changing it to suit the v2 provider will result in the resource being destroyed 
# and re-created since there is no way to update this value in place 
# (see https://github.com/terraform-providers/terraform-provider-azurerm/issues/5902). 
  
# To prevent this, add a lifecycle customisation and specify application_type as an attribute to ignore. Any attribute specified
# in the ignore_changes array will not be considered when creating a plan for an update, but they will still be part of creating
# a new resource.
  
resource "azurerm_application_insights" "appinsights" {
  name                = "${local.prefix}-appname"
  resource_group_name = azurerm_resource_group.main.name
  location            = azurerm_resource_group.main.location
  application_type    = "web"

  tags = local.tags

  lifecycle {
    ignore_changes = [
      application_type
    ]
  }
}

thank you very much for this!