TL;DR: `terragrunt clear-cache` doesn't exist anymore (removed in the 1.0 CLI redesign). A corrupt `.terragrunt-cache` is fixed by deleting the directory yourself; Terragrunt recreates it as needed.

```text
unknown command: "clear-cache". Terragrunt no longer forwards unknown commands by default.
```

## Steps

1. Find the caches: `find . -type d -name ".terragrunt-cache"`.
   Expected: you see how many there are (`run --all` leaves one per unit).
2. Delete them: `find . -type d -name ".terragrunt-cache" -prune -exec rm -rf {} +`.
   Expected: the directories are gone.
3. Re-run your command (e.g. `terragrunt run -- init`).
   Expected: modules re-download fresh; checksum/zip errors from the corrupt cache are gone.

## When this applies

- `unknown command: "clear-cache"` on Terragrunt 1.0+.
- Module load failures that smell like a corrupt cache: checksum mismatches, `failed to open zip archive`, stale module code after a source change.

## When it doesn't apply

- Below 1.1.3 with PARALLEL runs and checksum errors: upgrade first. Before 1.1.3, concurrent runs staged provider downloads at the same path and the first to finish could delete an archive the other was unpacking; clearing the cache doesn't fix a race.
- A moved tag serving new content under an old ref: re-pin to a commit SHA instead.

## Tool versions

Terragrunt 1.0+ (command removed in the redesign).

## Why it happens

Pre-1.0 Terragrunt forwarded unknown commands to terraform, so `clear-cache` felt like a built-in. The 1.x CLI no longer forwards, and the cache was deliberately left as plain scratch space on disk with no command wrapper.

## Edge cases

- For stale module code after changing `source` or bumping `ref`, prefer `terragrunt run --source-update -- init` over wiping the cache; it refetches in place.
- Set `TG_DOWNLOAD_DIR` to relocate the cache outside the working tree if scattered `.terragrunt-cache` dirs annoy you.