I created this basic smart contract on Rinkeby (uses OpenZeppelin ERC20PresetMinterPauser preset), minted 1m FOO, then added liquidity on Uniswap v2 with 10 ETH and 1m FOO. I then swapped 1 ETH for 90,661 FOO.

However, if I try to swap back, it says "Price Impact Too High", no matter how little amount of FOO I specify:

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In fact, the info balloon says 0% price impact, so this makes it even more odd:

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Any help appreciated. Of course, I set my price slippage to 30% to make sure, but there's clearly something else going on here.

  • Hi, did you check the gas price or gas amount you've sending ? May 28, 2021 at 21:36
  • @defikintaro You didn't read the question properly. This is way before that stage.
    – Neo
    May 29, 2021 at 0:45

2 Answers 2


I contacted Uniswap support on Discord, and they said it's a known issue on testnets due to them using "fake dollar prices", and it can be worked around by enabling Expert Mode, which I did, and it allowed me to 'Swap Anyway'. The issue is described in this GitHub issue - slightly different issue, but same root cause.


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  • Link only answer are discouraged. Please write the answer and only use the link to expand the details.
    – Ismael
    Jan 2, 2022 at 17:53

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