I’m having trouble creating NFTs using the Hedera Token Service and keep running into signature validation issues. Every time I try to mint a new token, the system throws an invalid signature error even though I think I’m following the documentation correctly.
I’ve been working with the HTS API and trying to set up the proper signing process, but something seems to be wrong with how I’m generating or formatting the signature. The error occurs during the token creation step and I can’t figure out what’s causing the signature to be rejected.
Has anyone else encountered this problem when working with Hedera’s NFT minting functionality? I’m wondering if there’s a specific way the signature needs to be structured or if I’m missing a step in the authentication process. Any guidance on the correct signature format for HTS would be really helpful.
Oh interesting, I’ve hit this before too! First thing - are you serializing all fields in the exact same order when creating the signature vs submitting? That’s what tripped me up.
What SDK are you using? The JavaScript and Java SDKs handle signing differently sometimes. Are you signing client-side or server-side?
Try logging the actual transaction bytes before signing to see if they look right. Sometimes there’s weird encoding issues you won’t catch until you dump the raw data.
What’s the exact error message? Does it say “INVALID_SIGNATURE” or something more specific? That’ll tell us if it’s a formatting issue or key mismatch.
make sure u check if the admin key is included in ur signatures. you usually need both ur account key & admin key. oh, and double check the network ur on, mixed up testnet & mainnet can mess up sig validation.
Had the same problem when I started with HTS. Turned out my transaction fee calculation was wrong. Your signature validation fails if the fees are off or you’re not freezing the transaction properly before signing. The timestamp thing got me too - don’t make your transaction validity too short and check that your system clock is synced. I kept getting signature errors that were actually timing issues. Double-check you’re using the right operator account with enough HBAR. The error messages suck at telling you if it’s a signature problem or account permissions. Run a simple balance query first to make sure your auth setup works before trying to create NFTs.