# Found unmapped fields during JSON-LD normalization

**URL:** <https://community.blockcerts.org/t/found-unmapped-fields-during-json-ld-normalization/2405>\
**Category:** Technical\
**Created:** [March 13, 2020, 1:58pm UTC](https://community.blockcerts.org/t/found-unmapped-fields-during-json-ld-normalization/2405 "2020-03-13T13:58:41Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![lemoustachiste](https://avatars.discourse-cdn.com/v4/letter/l/7c8e57/32.png) [@lemoustachiste](https://community.blockcerts.org/u/lemoustachiste)\
**Post date:** [March 18, 2020, 8:24pm UTC](https://community.blockcerts.org/t/found-unmapped-fields-during-json-ld-normalization/2405/2 "2020-03-18T20:24:41Z")

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Hi @dekts,

JSONLD normalization is a process where the document is parsed against a context definition.  
It’s being thrown here: [https://github.com/blockchain-certificates/cert-verifier-js/blob/master/src/inspectors/computeLocalHash.js#L88](https://github.com/blockchain-certificates/cert-verifier-js/blob/master/src/inspectors/computeLocalHash.js#L88)

Basically what this is telling you is that you are using fields that are not defined by the `@context` key of your certificate.  
You could try and define the keys that you are adding in your document in the same fashion as what Learning Machine does:

```auto
"@context": [
    "https://w3id.org/openbadges/v2",
    "https://w3id.org/blockcerts/v2",
    {
      "metadataJson": {
        "@id": "https://schemas.learningmachine.com/2017/blockcerts/metadata",
        "@type": "https://schemas.learningmachine.com/2017/types/text/json"
      },
      "displayHtml": {
        "@id": "https://schemas.learningmachine.com/2017/blockcerts/displayHtml",
        "@type": "https://schemas.learningmachine.com/2017/types/text/html"
      },
      "nonce": {
        "@id": "https://schemas.learningmachine.com/2017/blockcerts/nonce",
        "@type": "https://schema.org/Text"
      },
      "universalIdentifier": {
        "@id": "https://schemas.learningmachine.com/2017/blockcerts/identifier",
        "@type": "https://schema.org/Text"
      }
    }
  
]

```

I believe this should fix the issue for you

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_[View the full topic](https://community.blockcerts.org/t/found-unmapped-fields-during-json-ld-normalization/2405)._