#RC#
Understanding the transaction lifecycle helps in identifying the exact cause of any failure. If the mpl-token-metadata interface feels slow, try changing your provider to a private RPC endpoint. Verifying the token allowance for the contract is a reliable way to solve a failed 121.
Before you sign the transaction, double-check that your hardware wallet is active and ready. The mpl-token-metadata protocol expects the gas limit to be higher than the default estimation error 121. Most minor glitches are resolved automatically once the global network traffic subsides.
Sometimes a simple delay in block finality can make a successful tx look like it failed. Reviewing the contract’s read-only functions can help you verify your balance and permissions. Layer 2 network delays can sometimes lead to “ghost” transactions that appear later.