Terraform State Corruption in Azure — Recovered

Encountered this error?

Error: state snapshot was corrupt

The Problem

During a large-scale Azure deployment using remote state in Azure Blob Storage, a terraform apply was interrupted. The result: a corrupted terraform.tfstate.

Symptoms

• terraform plan or terraform apply fails immediately.
• terraform state pull shows unreadable or broken JSON.
• Azure CLI blob shows latest version is malformed.

Fix — Step-by-Step

Backup the Current (Corrupted) State

az storage blob download \
  --container-name tfstate \
  --name terraform.tfstate \
  --file backup-corrupt.tfstate \
  --account-name <storage_account>

List Older Versions (Versioning Must Be Enabled)

az storage blob list-versions \
  --container-name tfstate \
  --name terraform.tfstate

Download a Working Version

az storage blob download \
  --container-name tfstate \
  --name terraform.tfstate \
  --version-id <valid_version_id> \
  --file terraform.tfstate

Restore the Good State

az storage blob upload \
  --container-name tfstate \
  --name terraform.tfstate \
  --file terraform.tfstate \
  --account-name <storage_account> \
  --overwrite

Verification

terraform init
terraform plan

• Always enable blob versioning in your backend container.
• Use terraform state pull > backup.json as a safety net in CI/CD.
• Consider switching to state locking with azurerm backend or use tools like Terragrunt.