Looks like a outdated plugin. Upgrade to latest.
Fixed it with last upgrade 🙂
@psychobunny may have fixed this on latest master
@a_5mith yes found it , thanks !
Hi @javier-burón-garcía -- can't tell what the error is, since that's a generic Heroku error. Can you try running node app in Heroku console (I think it's called heroku run or something)?
Clearing the cache solved the problem immediately.