What is legacy mode?

Firstly, thank you for using arcK version 1.1. There has been some important changes from version 1.2, but rest assured you can extract or verify all archives you have already created.

From version 1.2, there has been breaking changes on any version 1.1.X.

However, to ensure backward compatibility, version 1.2 onwards can verify and extract archives created in previous versions. I have hundreds of gigabytes of arcK data stored is S3, so I am all in with this app and plan to maintain.

Archives created from 1.2 cannot be extracted or verified by any 1.1.X version.

Changes

• Due to changes to metadata file layout, which is not compatible with previous versions.

Can I upgrade

Yes, you can safely upgrade. Backwards compatibility is maintained.