Transaction Error while trying to mint NFT

Hi guys, I am new to Solana . I am trying to mint an NFT using the tutorial given in Solana cookbook as shown in this link NFTs | Solana Cookbook
i am getting the uri for the metadata in JSON from moralis but the JSON format is exactly the same as shown to be uploaded to arweave.
But I am getting the following error

Unhandled Runtime Error

Error: failed to send transaction: Transaction simulation failed: Error processing Instruction 2: custom program error: 0x26

Call Stack
Connection.sendEncodedTransaction

node_modules@solana\web3.js\lib\index.browser.esm.js (7336:0)

async Connection.sendRawTransaction

node_modules@solana\web3.js\lib\index.browser.esm.js (7297:0)

Can someone please explain what am I doing wrong???
It will be very helpful.