^^^ found my answer: <https://youtrack.jetbrains.c...

# server

[Michael Evans]

^^^ found my answer: https://youtrack.jetbrains.com/issue/KTOR-3358
There was a binary compatibility issue between my ktor version 1.6.5 and JDK 1.8
I updated my JVM target to 11 and updated my heroku dyno to the same JDK 11 and now we're up and running :)