Choose the correct Cardano CIP-25 metadata key encoding
An NFT can exist on chain even when a viewer fails to find its media metadata. Looking up the right policy and name with the wrong CBOR key types is enough to miss the record.
Inspect the metadata version under label 721
Locate the minting transaction metadata and its map at label 721. Check the declared version and distinguish a missing version, which uses the original version-one convention. Decode from the transaction metadata rather than a lossy JSON rendering when key types matter.
label 721 → policy → asset name → metadata fields
For version 1, policy and asset-name keys use text representations. Version 2 uses bytes for those keys. If the name bytes spell ART, a byte-string key containing ART and a CBOR text key ART remain distinct entries.
Match the mint and the asset
Verify the policy ID and asset name against the mint field and inspect the relevant transaction history for metadata updates under the standard. A media URI is an external reference whose availability does not follow from inclusion of the metadata. cips.cardano.org Cardano CIP-25