The Unparseable iamMember error in Google Cloud Platform (GCP) when using Terraform typically indicates that there's an issue with the format of the IAM member string in your Terraform configuration. This error means that GCP cannot understand the IAM member format you provided.

Here are the steps to resolve this issue:

Check IAM Member String Format:
Ensure that the IAM member string is correctly formatted. The typical formats are:

user:email@example.com
serviceAccount:service-account-name@project-id.iam.gserviceaccount.com
group:group-email@example.com
domain:example.com

Example:

resource "google_project_iam_member" "binding" {
  project = "your-project-id"
  role    = "roles/viewer"
  member  = "user:email@example.com"
}

Avoid Using Invalid Characters or Spaces:
Make sure there are no extra spaces or invalid characters in the member string.

Incorrect: user:email@ example.com (Note the space)
Incorrect: useremail@example.com (Missing user: prefix)
Correct: user:email@example.com

Verify the Role:
Ensure that the role you're trying to assign (roles/viewer in this case) is available and you have the necessary permissions to assign roles in the project.

Example Terraform Configuration:
Here is a correct example of a Terraform configuration for adding an IAM member to a project:
resource "google_project_iam_member" "binding" {
  project = "your-project-id"
  role    = "roles/viewer"
  member  = "user:email@example.com"
}

Use Valid Email Address:
Ensure the email address used in the member string is valid and corresponds to an actual user, service account, group, or domain within GCP.

Proper Quoting and Interpolation:
If you are using Terraform interpolation, ensure that it is correctly formatted. For example:
resource "google_project_iam_member" "binding" {
  project = var.project_id
  role    = "roles/viewer"
  member  = "user:${var.user_email}"
}

Update Terraform Provider:
Make sure you are using the latest version of the Google provider for Terraform. You can specify the provider version in your Terraform configuration:
terraform {
  required_providers {
    google = {cvgv bn
      source  = "hashicorp/google"
      version = ">= 3.5.0"
    }
  }
}

Check IAM Member Types:
Ensure you are using the correct member type for the resource. For example, the member type user should be used for individual user accounts.

Run Terraform Plan and Apply:
After making the necessary changes, run terraform plan to ensure there are no errors in the configuration, and then terraform apply to apply the changes.

If you follow these steps and ensure that your IAM member strings are correctly formatted and your Terraform configuration is correct, the Unparseable iamMember error should be resolved.