Some time ago we wrote that support for legacy workflows would cease in YouTrack 2019.1.
By “legacy” workflows we mean those written in the old Workflow Editor, which was an external application discontinued in version 2018.3.
We see that some of our customers are still using these legacy workflows. According to our feature usage statistics, almost 6.5% of YouTrack InCloud instances have one or more legacy workflows enabled. We’ve decided to keep them afloat for another 6 months, meaning that these workflows will stop working as of version 2019.3.
That said, we strongly encourage you to upgrade your legacy workflows as soon as possible. Not only is the old editor unavailable (meaning that you can’t change anything in your old rules), but the new API is also way more powerful and convenient. Some new features are unsupported in the old API; for example, you can’t implement action rules there.