I am testing the 0x api to get quote on Mumbai testnet. I want to swap BAL -> wETH. https://mumbai.api.0x.org/swap/v1/quote?buyToken=0x2e3A2fb8473316A02b8A297B982498E661E1f6f5&sellToken=0xE3981f4840843D67aF50026d34DA0f7e56A02D69&sellAmount=1000000000000000000

but don't know how to solve this issue:

  "code": 100,
  "reason": "Validation Failed",
  "validationErrors": [
      "field": "sellAmount",
      "code": 1004,

I tried with different sell amounts but none of them worked. I searched a lot about it on internet but none of them is effective. May anyone tell me what wrong am I doing here? How can I test 0x API on Mumbai testnet ?

2 Answers 2


0x Api fetchs liquidity from pools like Uniswap or 0x limit orders. If the token that you are testing in Mumbai don't have liquidty on Uniswap or similar protocol, the api is not able to give you a quote.

Possible solutions:

  1. Test with tokens with more liqudity. for instance, on Mumbai network you can use Matic <-> Weth
  2. Create a pool for that pair on Uniswap or Quickswap on Mumbai, with a sufficient amount of liquidity, something around 2 WETH and the equivalent in BAL

I personally suggest using the first solution, as getting testnet tokens from faucets could be a bit frustrating.


Check your buy token address! You can reference Mumbai polyscan explorer to confirm that this buy token address does not exist. https://mumbai.polygonscan.com/address/0x2e3A2fb8473316A02b8A297B982498E661E1f6f5

I believe you should use 0xA6FA4fB5f76172d178d61B04b0ecd319C5d1C0aa for wETH

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