Here are some ways to convert Elm 0.16 code that uses Effects.task into Elm 0.17.

The cases are sorted by priority, so use the first one that applies to your code.

Elm 0.16 example Elm 0.17 equivalent
task |> Task.toMaybe |> Effects.task task |> Task.perform (always Nothing) Just
task |> Task.toResult |> Effects.task task |> Task.perform Err Ok
task |> action |> Effects.task task |> Task.Extra.performFailproof action
task |> Effects.task task |> Task.Extra.performFailproof identity

The function performFailproof used in two places above is from package NoRedInk/elm-task-extra.

This recommendation comes from an elm-discuss posting by Janis Voigtländer on 2016-05-19.