Invalid value for input variable Terraform Origin: Platform & cloud OSI layer 7 · Application Last updated 5 Nov 2026

Terraform: Error: Invalid value for variable — "instance_type" must be a t3 type / The given value is not suitable for var.x declared at variables.tf:1,1-17: string required

A variable value failed its type or validation block.

Exact message you may see Error: Invalid value for variableThe given value is not suitable for var.x declared at variables.tf:1,1-17: string requiredError: Invalid value for input variable"instance_type" must be a t3 typeThis check failed: var.environment must be one of dev, stage, prod
Explore the map of this error Full error map →
Seen on: Terraform

Meaning

Read the condition message. Check the type (string, list(string), object), validation rules, and where the value comes from (-var, .tfvars, env TF_VAR_x, defaults). Complex types need correct HCL in tfvars/JSON; env vars for lists/maps must be HCL-formatted strings.

Common causes

  • Value type doesn't match declaration
  • Validation condition failed
  • tfvars not loaded (name must be terraform.tfvars or *.auto.tfvars or passed with -var-file)
  • TF_VAR_ environment variable with wrong format
  • Variable renamed

⚡ Quick fix

  1. Fix the value/type or the validation
  2. -var-file=prod.tfvars explicitly
  3. Use terraform console to test expressions

Detailed fix by platform

Terraform

  1. terraform plan -var-file=prod.tfvars

How to diagnose

  1. Type — Matches?
  2. Validation — Passing?
  3. Source — tfvars loaded?

🔧 Still not fixed?

Many errors look alike. If the steps above didn’t solve it, one of these is probably what you’re facing:

Where this error sits

Origin: Platform & cloud. Errors that are often confused with or caused by this one (click to open):

Error building ARM Config: obtain subscription from Azure CLI — Terraform: Error: building AzureRM Client: obtaining subscription ID / Please run 'az login' to setup account (Terraform)Error building ARM Co…error converting YAML to JSON — error converting YAML to JSON: yaml: line 12: did not find expected key (Kubernetes)error converting YAML…Invalid AWS Region — Terraform: Error: Invalid AWS Region: us-east-3 / Error: configuring Terraform AWS Provider: validating provider credentials: operation error STS: GetCallerIdentity (Terraform)Invalid AWS RegionInvalid function argument — Terraform: Error: Invalid function argument — Invalid value for "list" parameter: list of string required / Call to function "lookup" failed (Terraform)Invalid function argu…Missing required argument — Terraform: Error: Missing required argument — The argument "ami" is required, but no definition was found (Terraform)Missing required argu…No valid credential sources found (AWS provider) — Terraform: Error: No valid credential sources found — failed to refresh cached credentials, no EC2 IMDS role found / Error: configuring Terraform AWS Provider: no valid credential sources (Terraform)No valid credential s…No value for required variable — Terraform: Error: No value for required variable — The root module input variable "region" is not set, and has no default value (Terraform)No value for required…Output refers to sensitive values — Terraform: Error: Output refers to sensitive values — a root module output containing sensitive data must be explicitly marked as sensitive (Terraform)Output refers to sens…Invalid v…

Explore the map of this error Full error map →

🧠 Still stuck? Analyze your error

Paste the full message, response headers or stack trace — we'll detect the platform and point to the most likely cause.

💬 What worked for others

No tips yet — did something else fix this for you?

Share what worked for you

Tips are checked by an editor before they appear. Links are removed.