Navigating decentralized exchanges and liquidity pools can be rewarding, but it often comes with technical hurdles. If you've encountered an error while swapping tokens, adding liquidity, or interacting with smart contracts, you're not alone. This guide breaks down the most common issues users face — from slippage problems to gas limitations — and provides clear, actionable solutions.
Whether you're using MetaMask, Trust Wallet, or another Web3 wallet, understanding these errors helps you trade more efficiently and securely on Binance Smart Chain (BSC) and similar networks.
Common Exchange Errors and Fixes
INSUFFICIENT_OUTPUT_AMOUNT
The transaction cannot succeed due to error: BabyDogeRouter: INSUFFICIENT_OUTPUT_AMOUNT.
This error typically appears during a token swap when the expected output is too low compared to your slippage tolerance — or when pool liquidity is insufficient.
How to fix it:
- Refresh the page and retry the transaction later.
- Try swapping a smaller amount at once.
Increase your slippage tolerance:
- Tap the settings icon on the swap interface.
- Adjust slippage slightly upward (e.g., from 1% to 3–5%).
- Enter a simpler amount with fewer decimal places to reduce calculation complexity.
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INSUFFICIENT_A_AMOUNT or INSUFFICIENT_B_AMOUNT
Fail with error 'BabyDogeRouter: INSUFFICIENT_A_AMOUNT' or 'INSUFFICIENT_B_AMOUNT'
This occurs when you're trying to add or remove liquidity from a pool, but one of the two paired tokens doesn’t have enough balance in the pool.
Quick fixes:
- Refresh the page and attempt the action again.
If the issue persists:
- Open the settings menu on the liquidity page.
- Slightly increase your slippage tolerance.
- Retry the transaction.
Low liquidity pools are more prone to this — consider waiting for deeper liquidity or choosing a different pair.
EXPIRED Transaction Error
BabyDogeRouter: EXPIRED
This means the transaction deadline passed before you confirmed it. Most DEX interfaces set a default expiration time (often 20 minutes), and if you don’t sign quickly enough, the transaction fails.
Solution:
Generate the transaction and confirm it immediately. Avoid delays between initiating and approving the swap.
K Error – Price Impact from Token Fees
BabyDoge: K
This usually happens when swapping tokens that charge a transfer fee (like tDoge or tBTC). The router miscalculates output due to dynamic supply adjustments.
How to resolve:
- Switch the input/output fields: modify the “To” amount instead of “From.”
- This places an estimated value on the input field and accommodates fee deductions.
- Execute the swap right after making this change.
TRANSFER_FAILED
Execution reverted: BabyDoge: TRANSFER_FAILED
Tokens with restorative rebasing mechanisms (such as tDoge) require extra buffer because they reduce your sent amount via fees.
Recommended actions:
- Ensure you have at least 30% more of the token in your wallet than you intend to trade.
- If selling all holdings, try withdrawing 69% or 70% instead of 100%.
⚠️ Warning: This error may also indicate malicious activity:
- The token issuer might have frozen transfers.
- Selling could be restricted to whitelisted wallets only.
- Airdropped tokens triggering this error are often scams.
Always research token contracts before interacting. Never approve unknown contracts — your funds could be at risk.
High Price Impact & Transaction Failure
"Price impact too high" or "Transaction cannot succeed"
Both errors point to low liquidity in the trading pair.
Solutions include:
- Reduce the trade size.
- Increase slippage tolerance via the settings gear.
- Wait for higher liquidity before proceeding.
Large trades in shallow pools cause significant price movement, leading to failed transactions.
estimateGas Failed
This transaction would fail. Please contact support.
This critical error suggests something is wrong with how the contract handles gas estimation.
For removing liquidity from BNB pairs:
- Choose “Receive WBNB” instead of BNB and retry.
For token swaps:
- Contact the project team of the token involved.
- This issue usually stems from custom token logic that interferes with standard router functions.
Cannot Read Property 'toHexString' of Undefined
Unknown error: "Cannot read property 'toHexString' of undefined"
Frequently reported on mobile wallets like Trust Wallet, this bug disrupts swap execution.
Troubleshooting steps:
- Retry with increased slippage tolerance.
- If unresolved, switch to an alternative wallet such as SafePal or desktop MetaMask.
Some wallets handle complex contract calls better than others.
TransferHelper: TRANSFER_FROM_FAILED
Execution reverted: TransferHelper: TRANSFER_FROM_FAILED
This indicates either:
- Insufficient token balance.
- Missing or insufficient spending allowance granted to the contract.
Fix it by:
- Verifying your wallet holds enough tokens.
Approving the contract again:
- Revoke previous approval using tools like Unrekt.net.
- Re-approve with sufficient allowance.
Never skip allowance management — it’s essential for secure DeFi interaction.
Liquidity Pool & Staking Issues
Out of Gas Error
Warning! Error encountered during contract execution [out of gas]
You’ve set a gas limit too low for the network to process your transaction.
Solution:
- Manually increase the gas limit (not gas price) in your wallet.
- A limit of 200,000 is generally sufficient for most staking actions.
- Refer to your wallet’s documentation for gas adjustment instructions.
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BEP20: Transfer Amount Exceeds Allowance
Fail with error 'BEP20: transfer amount exceeds allowance'
This happens when a contract tries to move more tokens than you’ve approved it to spend.
Steps to resolve:
- Use Unrekt.net to revoke access for the problematic contract.
- Re-approve the contract without setting a spending cap (or set a safe limit).
- Retry the interaction.
Regularly auditing approvals enhances security and prevents failed transactions.
BEP20: Transfer Amount Exceeds Balance
Fail with error 'BEP20: transfer amount exceeds balance'
Common when unstaking from low-reward BabyDoge pools or attempting to send tokens already tied up in pending transactions.
If unstaking fails due to low rewards:
- Notify the team so they can top up the reward reserve.
For urgent exits, use emergencyWithdraw:
- Find the pool’s contract address (check your transaction history).
- Go to Write Contract on BscScan.
- Connect your wallet via “Connect to Web3.”
- Under “4. emergencyWithdraw,” enter
0and click Write.
⚠️ Note: This forfeits any unclaimed yield. Use only when necessary.
General Network & Wallet Errors
Provider Error – No Provider Found
Provider Error: No provider was found
Occurs when trying to connect via browser extensions like MetaMask or Binance Chain Wallet without having them installed or enabled.
Fix: Install and unlock your preferred wallet extension before connecting.
Unsupported Chain ID
Your wallet isn’t connected to the correct blockchain.
Solution: Switch to Binance Smart Chain (BSC).
Refer to your wallet’s guide for network setup steps if needed.
Buying Tokens with Transfer Fees
Tokens like tDoge apply a fee on every transfer, reducing received amounts.
To successfully swap:
- Click the settings icon.
- Set slippage tolerance equal to or higher than the token’s fee percentage (e.g., 10–15%).
This accounts for automatic deductions and prevents failed swaps.
Internal JSON-RPC Errors
MetaMask - RPC Error: Internal JSON-RPC error
Common causes:
insufficient funds for transfer: You lack enough BNB for gas fees. Deposit more BEP-20 BNB.estimateGas failed: May occur with certain tokens in MetaMask. Try using SafePal, Coinbase Wallet, or desktop browsers.
Always ensure adequate BNB balance for network fees when interacting with smart contracts.
ethjs-query Formatting Errors
Error: [ethjs-query] while formatting outputs from RPC
Examples:
"transaction underpriced"→ Increase gas limit or gas price."handle request error"→ Clear browser cache, increase slippage, and retry.
These often stem from temporary network congestion or misconfigured wallet settings.
Frequently Asked Questions (FAQ)
Q: What is slippage tolerance, and why does it matter?
A: Slippage tolerance is the maximum price change you accept during a trade. Low slippage in volatile or illiquid markets leads to failed swaps. Adjusting it slightly upward can prevent errors like INSUFFICIENT_OUTPUT_AMOUNT.
Q: Why do some tokens fail even with enough balance?
A: Even with sufficient balance, you must grant contracts permission to use your tokens via approval. Also, fee-charging tokens (like tDoge) may require buffer amounts or higher slippage settings.
Q: How can I avoid losing yield when unstaking?
A: Use standard withdrawal methods after harvesting rewards. Reserve emergencyWithdraw for urgent cases — it skips rewards distribution and returns only your principal.
Q: Is it safe to increase slippage above 5%?
A: Only do so if you trust the token and understand its mechanics. High slippage increases risk of loss from price volatility or malicious tokens.
Q: Can I recover funds after a failed transaction?
A: Yes — failed transactions consume gas but return your primary tokens. Always double-check approvals and contract addresses before confirming.
Q: Why does my wallet show ‘out of gas’ even with BNB?
A: You may have enough BNB, but the gas limit is set too low. Manually raise it in advanced settings (e.g., to 200,000) for complex operations like liquidity removal or staking.
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By understanding these common errors and their fixes, you can trade confidently across decentralized platforms. Always verify contract addresses, manage allowances responsibly, and use trusted tools to enhance both security and success rates.