Troubleshooting Errors
Common error messages. Use the sidebar ➡️to jump to the error you're seeing.
Sometimes you may find yourself facing a problem that doesn't have a clear solution. These troubleshooting tips may help you solve problems you run into.
Issues on the Exchange
INSUFFICIENT_OUTPUT_AMOUNT
The transaction cannot succeed due to error: LenoRouter: INSUFFICIENT_OUTPUT_AMOUNT. This is probably an issue with one of the tokens you are swapping.
the transaction cannot succeed due to error: execution reverted: lenorouter: insufficient_output_amount.
You're trying to swap tokens, but your slippage tolerance is too low or liquidity is too low.
Refresh your page and try again later.
Try trading a smaller amount at one time.
Increase your slippage tolerance:
Tap the settings icon on the liquidity page.
Lastly, try inputting an amount with fewer decimal places.
INSUFFICIENT_A_AMOUNT or INSUFFICIENT_B_AMOUNT
Fail with error 'LenoRouter: INSUFFICIENT_A_AMOUNT' or Fail with error 'LenoRouter: INSUFFICIENT_B_AMOUNT'
You're trying to add/remove liquidity from a liquidity pool (LP), but there isn't enough of one of the two tokens in the pair.
Refresh your page and try again, or try again later.
Still doesn't work?
Tap the settings icon on the liquidity page.
Increase your slippage tolerance a little and try again.
LenoRouter: EXPIRED
The transaction cannot succeed due to error: LenoRouter: EXPIRED. This is probably an issue with one of the tokens you are swapping.
Try again, but confirm (sign and broadcast) the transaction as soon as you generate it.
This happened because you started making a transaction, but you didn't sign and broadcast it until it was past the deadline. That means you didn't hit "Confirm" quickly enough.
Leno: K
The transaction cannot succeed due to error: Leno: K. This is probably an issue with one of the tokens you are swapping.
Try modifying the amount on “To” field. Therefore putting "(estimated)" symbol on “From”. Then initiate the swap immediately.
This usually happen when you are trying to swap a token with its own fee.
Leno: TRANSFER_FAILED
The transaction cannot succeed due to error: execution reverted: Leno: TRANSFER_FAILED.
Make sure you have 30% more tokens in your wallet than you intend to trade, or try to trade a lower amount. If you want to sell the maximum possible, try 70% or 69% instead of 100%. Caused by the design of Restorative Rebase tokens like tDoge or tBTC. Understand how restorative rebase tokens work.
Another possible cause of this issue is the malicious token issuer just suspended the trading for their token. Or they made selling action only possible for selected wallet addresses. Please always do your own research to avoid any potential fraud. If the token you are trying to swap but failed with this error code is coming from an airdrop, that is most likely a scam. Please do not perform any token approval or follow any links, your fund may be at risk if you try to do so.
Transaction cannot succeed
Try trading a smaller amount, or increase slippage tolerance via the settings icon and try again. This is caused by low liquidity.
Price Impact too High
Try trading a smaller amount, or increase slippage tolerance via the settings icon and try again. This is caused by low liquidity.
estimateGas failed
This transaction would fail. Please contact support
If you got this error while removing liquidity from a BNB pair:
Please select "Receive WBNB" and retry.
If you got this error while trying to swap:
Please contact the project team of the token you're trying to swap. **** This issue must be resolved by the project team.
Cannot read property 'toHexString' of undefined
"Unknown error: "Cannot read property 'toHexString' of undefined"
When trying to swap tokens, the transaction fails and this error message is displayed. This error has been reported on mobile devices using Trust Wallet.
Attempt the transaction again with increased slippage allowance.
If 1. does not resolve your problem, consider using another wallet such as SafePal for your transaction.
Execution reverted: TransferHelper: TRANSFER_FROM_FAILED.
The transaction cannot succeed due to error: execution reverted: TransferHelper: TRANSFER_FROM_FAILED.
When trying to swap tokens, the transaction fails and this error message is displayed. This error has been reported across platforms.
Check to make sure you have sufficient funds available.
Ensure you have given the contract allowance to spend the amount of funds you're attempting to trade with.
Issues with Sweet Pools
BEP20: burn amount exceeds balance
Fail with error 'BEP20: burn amount exceeds balance'
You don't have enough SWEET in your wallet to unstake from the LENO-LENO pool.
Get at least as much SWEET as the amount of LENO that you’re trying to unstake.
Buy SWEET on the exchange. If you want to unstake 100 LENO, you need at least 100 SWEET.
Try unstaking again.
If that still fails, you can perform an “emergencyWithdraw” from the contract directly to unstake your staked tokens.
In section “4. emergencyWithdraw”, enter "0" and click “Write”.
This will unstake your staked tokens and lose any uncollected LENO yield.
This will lose any yield that you haven’t harvested yet.
To stop this happening again, don’t sell your SWEET. You still need it to unstake from the “Stake LENO Earn LENO” pool.
This error has happened because you have sold or transferred SWEET tokens. SWEET is minted in a 1:1 ratio to LENO when you stake in the LENO-Sweet Pool. SWEET must be burned at a 1:1 ratio to LENO when calling leaveStaking (unstaking your LENO from the pool), so if you don't have enough, you can't unstake from the pool.
Out of Gas error
Warning! Error encountered during contract execution [out of gas]
You have set a low gas limit when trying to make a transaction.
Try manually increasing the gas limit (not gas price!) in your wallet before signing the transaction.
A limit of 200000 is usually enough.
The above example is from Metamask; check your wallet's documentation if you aren't sure how to adjust the gas limit.
BEP20: transfer amount exceeds allowance
Fail with error 'BEP20: transfer amount exceeds allowance'
Use Unrekt.net to revoke approval for the smart contract you're trying to interact with
Approve the contract again, without setting a limit on spend allowance
Try interacting with the contract again.
BEP20: transfer amount exceeds balance
Fail with error 'BEP20: transfer amount exceeds balance'
You're probably trying to unstake from a Sweet Pool with low rewards in it. Solution below.
If not, you may be trying to send tokens that you don't have in your wallet (for example, trying to send a token that is already assigned to a pending transaction). In this case, just make sure you have the tokens you're trying to use.
Firstly, let the team know which pool you're trying to unstake from, so they can top up the rewards. If you're in a hurry to unstake and you don't mind losing your pending yield, try an emergencyWithdraw:
You can perform an “emergencyWithdraw” from the contract directly to unstake your staked tokens.
Find the contract address of the Sweet Pool you're trying to unstake from. You can find it in your wallet's transaction log.
Go to https://bscscan.com/ and in the search bar, enter the contract address.
Select Write Contract.
In section “3. emergencyWithdraw”, and click “Write”.
This will unstake your staked tokens and lose any uncollected yield.
This will lose any yield that you haven’t harvested yet.
Issues with Prediction
Other issues
Provider Error
Provider Error No provider was found
This happens when you try to connect via a browser extension like MetaMask or Binance Chain Wallet, but you haven’t installed the extension.
Install the official browser extension to connect, or read our guide on how to connect a wallet to LenoSwap.
Unsupported Chain ID
Switch your chain to BNB Smart Chain. Check your wallet's documentation for a guide if you need help.
Already processing eth_requestAccounts. Please wait.
Make sure you are signed in to your wallet app and it's connected to BNB Smart Chain.
Issues buying SAFEMOON and similar tokens
To trade SAFEMOON, you must click on the settings icon and set your slippage tolerance to 12% or more. This is because SafeMoon taxes a 10% fee on each transaction:
5% fee = redistributed to all existing holders
5% fee = used to add liquidity
This is also why you might not receive as much of the token as you expect when you purchase. Read more on How to Buy Safe Moon.
Internal JSON-RPC errors
"MetaMask - RPC Error: Internal JSON-RPC error. estimateGas failed removeLiquidityETHWithPermitSupportingFeeOnTransferTokens estimateGas failed removeLiquidityETHWithPermit "
Happens when trying to remove liquidity on some tokens via Metamask. Root cause is still unknown. Try using an alternative wallet.
Internal JSON-RPC error. { "code": -32000, "message": "insufficient funds for transfer" } - Please try again.
You don't have enough BNB to pay for the transaction fees. You need more BEP-20 network BNB in your wallet.
Error: [ethjs-query]
Error: [ethjs-query] while formatting outputs from RPC '{"value":{"code":-32603,"data":{"code":-32000,"message":"transaction underpriced"}}}"
Increase the gas limit for the transaction in your wallet. Check your wallet's documentation to learn how to increase gas limit.
Swap failed: Error: [ethjs-query] while formatting outputs from RPC '{"value":{"code":-32603,"data":{"code":-32603,"message":"handle request error"}}}'
Cause unclear. Try these steps before trying again:
Increase gas limit
Increase slippage
Clear cache
Issues with Profile
Oops! We couldn't find any Leno Collectibles in your wallet.
We're investigating the logic behind this issue. Meanwhile please try the workaround.
Go to “Collectible” page, then come back to profile page. If you can’t find the link, go to https://lenoswap.com/collectibles directly.
Retry profile creation.
Checking username keeps spinning
There are two possible causes.
You have multiple wallets installed on the browser.
Network issue.
Root cause: You have multiple wallets installed on the browser. It may make a conflict between wallets. This is out of LenoSwap's control and we can do nothing.
Have only single wallet installed on browser, remove the others.
Reconnect the wallet and retry setting username again.
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