App on Heroku crashed after update from v.3.3.4 to v.3.4.0

Looks good :thinking: did you update progressively from a much older version in one go? If so I think you might be missing a modification.

Specifically this one:

https://strapi.io/documentation/developer-docs/latest/migration-guide/migration-guide-beta.19-to-beta.19.4.html#route-syntax-changes

Usually when I see references on MongoDB projects to that error, it’s old issues from when we implemented this.