ALLOWED_LANGUAGE_VERSIONS error when trying to run sandbox with LF version 1.dev

I’m getting the following error when trying to start sandbox from SDK version 2.0.0-snapshot.20211201.8538.0.1d0ff3cc, targeting Daml-Lf version 1.dev:

ALLOWED_LANGUAGE_VERSIONS(8,f1c2205b): Disallowed language version in package de586dc8cef868cef5c3d10a92d74da3e5ee0485df37cd509d0dc98f9b01303c: Expected version between 1.6 and 1.14 but got 1.dev

Do I need to explicitly allow this somehow? I didn’t see any option to do so.

Hi @georg, you can allow Daml-LF 1.dev by starting Sandbox with --daml-lf-dev-mode-unsafe. As the name suggests allowing 1.dev is highly unsafe in production but for experiments it’s of course perfectly fine and we’re happy to receive feedback on 1.dev.