Error codes / Metaplex Token Metadata
NotMintAuthority
Metaplex Token Metadata · Custom(9) · 0x9
custom program error: 0x9
What it means
You must be the mint authority and signer on this transaction
What to do
The error name is the program's own diagnosis. Paste the failed transaction into TxWhy to see which instruction raised it and with which accounts.
Have the transaction that failed with this?
Paste its signature. TxWhy shows the exact instruction and inner call that raised the error, and rebuilds the transaction when the cause is one it can fix (compute limit, expired blockhash, priority fee, stale swap quote).
Code 9 means something else in other programs
Custom codes are private to each program. Check which program actually raised it: it is the innermost failed call, not necessarily the program you called.