Solana

Rent and Account Creation

• Every Solana account must hold a minimum SOL balance (~0.00089 SOL for basic accounts) to be rent-exempt — accounts below this get deleted
• Sending SOL to a new address that has never received anything will fail if the amount doesn't cover rent-exempt minimum
• Token accounts require separate rent deposits — each new token type a wallet holds costs ~0.002 SOL to create
• Close unused token accounts to recover rent: spl-token close returns the SOL to owner

Token Accounts (SPL Tokens)

• Unlike Ethereum, Solana wallets don't automatically hold tokens — each token needs an Associated Token Account (ATA) created first
• First-time token transfers must create the recipient's ATA — sender pays ~0.002 SOL account creation fee
• "Account not found" error usually means the ATA doesn't exist yet, not that the wallet is invalid
• One wallet can have multiple ATAs for the same token (non-associated) — always use the ATA address for standard transfers

Transaction Fees and Priority

• Base fee is ~0.000005 SOL (5000 lamports) per signature — much cheaper than Ethereum
• Priority fee = compute units × price in micro-lamports — set via SetComputeUnitPrice instruction
• During congestion (NFT mints, popular DEX), transactions without priority fees get dropped, not queued
• Default compute unit limit is 200k per instruction — complex programs may need SetComputeUnitLimit to increase

Transaction Lifecycle

• Solana transactions expire after ~60 seconds (based on blockhash age) — no permanent mempool like Bitcoin/Ethereum
• "Dropped" means tx was never included and expired. "Failed" means it was included but reverted. Completely different outcomes
• If transaction shows "confirmed" but not "finalized", wait — finalized means 31+ confirmations and is irreversible
• Preflight simulation catches most errors before broadcast — disable with skipPreflight: true only if you know why

Common Error Messages

• "Insufficient funds for rent" — account would drop below rent-exempt minimum after transaction
• "Account not found" — the account doesn't exist on-chain (never created or was closed)
• "Blockhash not found" — transaction expired, need fresh blockhash and re-sign
• "Program failed to complete" — smart contract error, check logs with solana confirm -v

RPC and APIs

• Public RPCs (api.mainnet-beta.solana.com) have strict rate limits — production apps need paid RPC (Helius, QuickNode, Triton)
• getRecentPrioritizationFees RPC gives current priority fee market — essential for landing txs during congestion
• Solscan.io and Solana.fm are the main block explorers — both show decoded instruction data
• For token metadata (name, symbol, image), query Metaplex on-chain or use Helius/SimpleHash APIs

Wallet and Security

• Phantom, Solflare, Backpack are the main wallets — each has slightly different transaction simulation UI
• "Approve" prompts in Solana can drain entire wallet if malicious — read the simulation carefully
• Burner wallets are common practice for minting/airdrops — never connect main wallet to unknown sites
• Unlike Ethereum's infinite approvals, most Solana programs take tokens directly — no separate revoke step needed