If you’ve attempted a SWAP and came across the ALLOWANCE_NOT_ZERO error, this article is for you. Here, we’ll break down the cause of this error and what can be done to fix it so you can move forward with your transactions.
What is the ALLOWANCE_NOT_ZERO error?
The Allowance Not Zero error is generally caused when choosing the output amount and not the input.
With our troubleshooting steps below, we have a few suggestions to correct the error but most can generally be solved by filling in the input amount for your anticipated swap vs. the output.
How to fix:
The biggest thing to avoid this error is to recall what we mentioned earlier. You’ll want to focus on filling in the input amount (top) for your swap vs. the output (bottom).
By selecting the output amount (a lower value on the swap page), it can create more errors due to slippage compared to the input amount.
Another solution to improve the experience is to turn on Flashbots in your swap settings. Turning on flashbots does is it prevents you from losing gas on a failed transaction.