Hello and thank you beforehand for your time! I read a lot before posting and could not find a solution to this. Pool.pm is complaining about the metadata '721' throwing an error: "Expecting an OBJECT with a field named 721"

I first thought I made the transaction using a different policy id than the metadata like in this post: NFT Image not Displaying in Pool.pm after using the 721 Metadata Standard But as you can see from https://cardanoscan.io/transaction/c02c4db6bc9b2b9f3adcac930559368f7c2a4f00a2a53fc8661fae3b5ce844b2?tab=metadata the policy id matches the one on the metadata. The metadata I used is:

  "777": {
    "prc": "0.5",
    "addr": [

  "721": {
    "3e3a9f39933d04bd854527801f615d35d1cbe1b0344d482af20343ae": {
      "ShaveandTattooed": {
        "Name": "Shave and Tattooed",
        "Artist": "Marvin Lunas",
        "Image": "QmRTJUU8MUw5rUzES6XJd5RiA55K9seVAWU3tTkS8UoQYi",
        "mediaType": "image/png",
        "Description": "Description",
        "files": [
            "mediaType": "image/png",
            "src": "QmUhgW6c8MKmzZKMNtr8Sfvb8UjqM3bgCh6X1upDCNAgHH",
            "Name": "Shave and Tattooed"
        "ID": "1",
        "Minting Platform": "https://adamagic.io"
    "Version": "1.0"

I have no idea what is causing this issue because I did use the same template before and it was all good. It also has a problem while loading the thumbnail and at this point, I think the problem is on me.

Once again, thank you all for your time and effort! Cheers


1 Answer 1


It's showing up for me alright on pool.pm: https://pool.pm/asset1xpdk028mq57te9dkg62rvy79nv2mhl4zr78xgn

Might have been just a temporary issue while data was populating?

There's a testing tool here, that you can use to verify it works: https://pool.pm/test/metadata

Here it's populated with your metadata: Link

When you remove or rename the "721" object you'll see your exact error show up: "Expecting an OBJECT with a field named 721".

So if this is the place you're seeing it, there might be just a simple syntax error in the json you're putting in here.

Just some potential minor improvements to the metadata:

According to the spec at https://cips.cardano.org/cips/cip25/#specification you should use lowercase attribute names like "name" and "image" instead of "Name" or "Image".

And for the image hashes I'd add "ipfs://" as a prefix to make it more clear where to look for them, but it does usually work fine without.

Anyways looks like it all works fine on my side as is 👍

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