Swapping Legacy sUSD on Optimism

I had some old sUSD tokens sitting in my wallet on Optimism. They'd been there for a while, doing nothing. Today I finally dealt with them, and it turned into a small adventure worth documenting.

What's sUSD?

sUSD is a synthetic dollar created by Synthetix. It's collateralized by SNX tokens at a 3:1 ratio, meaning for every sUSD in circulation, there's $3 worth of SNX backing it. It's one of the OG DeFi stablecoins, and for a long time it worked well enough.

The specific token I had was on Optimism: contract 0x8c6f28f2F1A3C87F0f938b96d27520d9751ec8d9.

Trying Uniswap First

My first attempt was Uniswap. But when I searched for sUSD there, I found a different contract: 0x57ab1ec28d129707052df4df418d58a2d46d5f51. That's the same one listed on CoinGecko. My tokens weren't detected. Different contract, different token version. Dead end.

Swapping on Velodrome

So I went to Velodrome, which is the main DEX on Optimism. Found the sUSD pool and tried to swap to USDT.

It kept failing. Transaction after transaction, automatically rejected. I had no idea why.

Turns out the issue was related to Velodrome's "smart account" feature. The swap kept getting rejected after I declined the smart account prompt. I didn't connect the two at first.

The Smart Account Fix

Velodrome offers a "smart account" upgrade that uses account abstraction: faster transactions, lower fees, and the ability to pay gas with any token you hold.

What finally worked: I moved the sUSD to a different wallet, enabled the smart account there, and the swap went through.

The exchange rate wasn't great (sUSD is depegged, so you're getting roughly $0.85 per sUSD instead of $1), but the tokens are finally out of limbo and into something usable.

The Lesson

The real takeaway here isn't about sUSD specifically. It's about DeFi protocols in general.

Protocols evolve. They deprecate old systems, migrate to new chains, change token contracts. If you're holding tokens and not paying attention, you can end up with assets that are harder to move or worth less than you think.

A few things I'll do differently:

• Check governance channels periodically. Even for protocols where I'm just holding tokens, not actively participating.
• Don't let tokens sit indefinitely. If you're not using them, either put them to work or convert them to something you actively manage.
• Understand the chain you're on. Legacy tokens on L2s can be especially tricky because not every DEX recognizes the same contract.
• Try different DEXes. When one doesn't work (Uniswap couldn't find my token), another might (Velodrome did).