---
version: "v1.0.8"
category: "experiments-updated"
---

#### `cas` — `update_source_with_cas` requires a literal source string

When a catalog `unit`, `stack`, or `terraform` block set `update_source_with_cas = true` with a `source` that was not a literal string, rewriting silently produced a wrong source. Interpolation such as `"../units/${local.name}"` had the interpolated portion dropped, leaving a bare prefix; a reference such as `local.foo` resolved to the directory containing the block itself. In both cases stack generation packaged the wrong directory without any error.

Stack generation now fails with an error explaining that `update_source_with_cas` requires a literal source string. Non-literal expressions, including interpolation, function calls, and references like `local.foo`, are rejected.
