Hi @witos,

If you run your 2016 workspaces in FME 2019 as is, they will still use 2016 versions of transformers, readers, and writers. For anything that can be upgraded, you will find them in the Navigator under Transformers, as Upgradeable Transformers where you can right click and upgrade them (this occurs on a transformer by transformer basis):

You can right click on readers and writers to update them as well. Generally we recommend to upgrade workspaces only if necessary and then slowly with frequent testing if so, as improvements in transformers mean that how they used to work may have changed. There's an article here that explains this in a bit more detail.

There's also a great discussion from this Q&A here about the best way to upgrade a workspace. In particular, take a look at Mark's answer if you're interested in reading into it a bit more.