Breaking Changes
cdktf synth --json Option #1640If you are using cdktf synth --json <stack-name> to get the synthesized JSON configuration for your Stack, you will now need to run cdktf synth && cat ./cdktf.out/stacks/<stack-name>/cdk.tf.json instead. The ./cdktf.out part is your output directory (set by cdktf.json or via the --output flag).
In an effort to streamline the interfaces of resources, computed attributes of the type list and set are now modeled as a separate ComplexList type instead of being a method that directly takes an index and returns an item. This change also did change the type of the index from string to number.
// previously
const firstItemId = resource.listAttribute("0").id;
// new
const firstItemId = resource.listAttribute.get(0).id;
const firstItem = resource.listAttribute.get(0); // now possible
first_item_id = resource.list_attribute("0").id;
Fetched April 8, 2026