Unknown argument \"formatString\" on field \"date\" of type \"frontmatter_2\".

[kripod]

Since upgrading from Gatsby v1.9.33 to v1.9.39, I get the error message showcased in the issue title when running a query similar to the gatsby-plugin-remark usage example:

allMarkdownRemark {
  edges {
    node {
      frontmatter {
        date(formatString: "YYYY-MM-DD")
      }
    }
  }
}

I'm not sure about the cause, but found an issue which might be related to the problem: #2096

[KyleAMathews]

The problem is your date field isn't being inferred as a "date".

I'd look at your posts to see if some of the fields aren't valid. These are the supported formats

gatsby/packages/gatsby/src/schema/infer-graphql-type.js

Line 45 in 7945bc5

const ISO_8601_FORMAT = [

[kripod]

My date formats were correct, but it turns out that dates now have to be put inside quotes, so

• date: 2000-01-01 doesn't work
• date: "2000-01-01" works

[kripod]

After a bit of thinking, I'm not sure about when quotes should be used inside a front matter. According to the Jekyll Front Matter docs, quotes should not be necessary.

[KyleAMathews]

They're not. Thanks easiest way for me to help you would be if you could build me a site reproducing the problem like Joseph did here #2096 (comment)

[kripod]

Clone this repository at 865a0ad75214e85304edbf72906abde6b3a1d040 and then run yarn upgrade-interactive, selecting everything related to Gatsby. I've put all the dates inside quotes in my next commit.

[KyleAMathews]

Thanks for the reproduction! Problem was I didn't actually fix the issue in my last PR… I used Date.toString instead of Date.toJSON which meant that the serialized dates weren't recognizable as dates later when inferring the GraphQL schema!

New PR is up fixing this, thanks again for testing! Also nice looking site :-)

[rchrdnsh]

I'm running into this now, not sure what to change, tho.

[rchrdnsh]

oh, i get it now...I have to put a 0 before a date that does not have two digits, like the first 9 days of a month...that's a bit annoying... :-/

[discordianfish]

@KyleAMathews It would be so, so useful if the error returned which document it happened on.

[chancesmith]

Agreed! What post do I need to fix?