yarn dev failed with exit code 1. Invalid headers found

[kudarukuni]

value in header item must be string for route {"source":"/blog/:slug*","headers":[{"key":"x-forwarded-proto","value":"https"},{"key":"x-forwarded-host"},{"key":"host"}]}

value in header item must be string for route {"source":"/explore/:slug*","headers":[{"key":"x-forwarded-proto","value":"https"},{"key":"x-forwarded-host"},{"key":"host"}]}

[MarcusWentz]

I have the same issue with:

npm run dev

Any updates on how to fix this?

[MarcusWentz]

It looks like an

.env 

file is missing since there are many environmental variables referenced that are not defined.

Thank you @johannafransn for finding this.

[johannafransn]

And the current .env-sample file does not include many of the next.config.js variables that are referenced in the headers. Sample env file should be updated to reflect all variables 👍