There are many breaking changes when moving from lisk-sdk 2.X to 3.X, at this moment there is no documentation for 3.X.
This commit might be of help https://github.com/thepool-io/ldice/commit/632f94d7515b851217d258a0f5c9503466c105f2
There is also a page in the documentation which covers what needs to be done when updating from Lisk SDK 2.x to 3.x: https://lisk.io/documentation/lisk-sdk/reference/changelog.html