ABOUT Uniswap?

Uniswap is an automated ethereum-based crypto exchange with its own governance token, UNI.Uniswap is a leading decentralized crypto exchange that runs on the Ethereum blockchain.

The Uniswap platform was built in 2018 on top of the Ethereum blockchain, the world’s second-largest cryptocurrency project by market capitalization, which makes it compatible with all ERC-20 tokens and infrastructure such as wallet services like MetaMask and MyEtherWallet.

The vast majority of crypto trading takes place on centralized exchanges such as Coinbase and Binance. These platforms are governed by a single authority (the company that operates the exchange), require users to place funds under their control and use a traditional order book system to facilitate trading.

For example, if you wanted to sell one bitcoin (BTC) at a price of $33,000 on a centralized exchange, you’d need to wait for a buyer to appear on the other side of the order book who’s looking to buy an equal or higher amount of bitcoin at that price.

What is Uniswap?

Uniswap is a completely different type of exchange that‘s fully decentralized – meaning it isn’t owned and operated by a single entity – and uses a relatively new type of trading model called an automated liquidity protocol.

Uniswap is also completely open source, which means anyone can copy the code to create their own decentralized exchanges. It even allows users to list tokens on the exchange for free. Normal centralized exchanges are profit-driven and charge very high fees to list new coins, so this alone is a notable difference. Because Uniswap is a decentralized exchange (DEX), it also means users maintain control of their funds at all times as opposed to a centralized exchange that requires traders to give up control of their private keys so that orders can be logged on an internal database rather than be executed on a blockchain, which is more time consuming and expensive. By retaining control of private keys, it eliminates the risk of losing assets if the exchange is ever hacked. According to the latest figures, Uniswap is currently the fourth-largest decentralized finance (DeFi) platform and has over $3 billion worth of crypto assets locked away on its protocol.

How to use UniSwap:

A step-by-step beginner's guide?

There are several ways in which users can get started using the Uniswap DEX such as the MetaMask wallet, the Trust Wallet, and the Coinbase wallet. How to use Uniswap with Metamask?

Steps to use Uniswap with Metamask are listed in the figure below:

1.Download the Metamask wallet from metamask.io. First-time users will be prompted to add the extension to their browser.

2.Upon doing so, users will have to create a new wallet and write down their Secret Recovery phrase. Write these words down in a safe and secure place, preferably in a hard notebook for safekeeping at home.Do NOT take a photo or a screenshot of your Secret Recovery phrase.Anyone with access to your phone or photos on your computer will be able to swipe your funds.

3.Next, head over to uniswap.org, and click on the pink "Launch App" button on the top-right-hand corner. (Always check that the address is valid. Upon confirming the validity of the address, users should bookmark the ones they plan to return to at a later date.)

4.Connect the Metamask wallet to Uniswap.

5.Select the desired token for swapping, as well as the token in possession to swap against.

6.Input the amount, and click "Swap".

7.Once the swap has been confirmed, the app might prompt users to add the swapped token to the Metamask wallet. This is because Metamask does not automatically show the balance of tokens that have been added. Users are required to add these tokens manually.

How to use Uniswap with Coinbase?

The Coinbase approach might be less intimidating for U.S. citizens who are already familiar with the platform. First-time users should start the steps below after successfully opening a Coinbase account. Those who already have an account can start with Step 1.

1.After downloading Coinbase wallet from the mobile app store, complete the setup process.

2.As with the Coinbase wallet, users will have to deposit an ERC-20 token into their wallet.

3.In the bottom-left-hand corner, the same four squares from the Uniswap app will be visible, representing the DApps explorer.

4.In the DApps explorer, users can search for the Uniswap protocol. Clicking on the protocol will present the user with the swap page.

5.From the swap page, users can search for their desired coin. If it's not a popular token, users will have to import it.

6.Once the desired amount is selected, users can swap for the desired token.

How to use Uniswap with Trust Wallet?

Trust Wallet is one of the most popular mobile wallets, and there's a reason for that. Trust Wallet is easy to use, friendly and offers a range of tools for users. Below are the steps for using Uniswap with Trust Wallet.

1.After downloading Trust Wallet from the mobile app store, complete the setup process.

2.As with the Coinbase wallet, users will have to deposit an ERC-20 token into their wallet.

3.In the bottom-left-hand corner, the same four squares from the Uniswap app will be visible, representing the DApps explorer.

4.In the DApps explorer, users can search for the Uniswap protocol. Clicking on the protocol will present the user with the swap page.

5.From the swap page, users can search for their desired coin. If it's not a popular token, users will have to import it.

6.Once the desired amount is selected, users can swap for the desired token.

One critical deterrent for new Uniswap users is the exorbitant Uniswap fees. Because Uniswap lives on the Ethereum blockchain, it relies on ETH for gas fees. Due to Ethereum's design, greater congestion leads to higher gas fees because it fuels a bidding war between users competing to have their transactions inserted first into the next block.

Advantages and Disadvantages of Uniswap.

Pros

Enables the decentralized exchange of many digital assets

Smart contracts enable more secure asset trading

Uniswap users can earn UNI by agreeing to stake their cryptocurrency holdings

Decentralized governance of the Uniswap platform enables anyone to participate

Cons

Uniswap only supports the exchange of Ethereum-compatible cryptocurrencies

Users must own ETH to pay transaction processing fees

Using a decentralized exchange requires a compatible, self-hosted wallet

Uniswap vs. PancakeSwap

Uniswap and PancakeSwap are both decentralized exchanges that facilitate digital asset trading. Both use tokens—UNI and CAKE, respectively—to incentivize users to provide liquidity.

PancakeSwap and Uniswap operate on different blockchain platforms. Uniswap uses the Ethereum platform, whereas PancakeSwap uses the Binance Smart Chain. Uniswap supports the exchange of Ethereum-compatible tokens that adhere to the ERC-20 standard, while PancakeSwap enables the exchange of Binance-compatible tokens that comply with Binance's BEP-20 technical standard.

Uniswap Troubleshooting Guide.

1. Failed Transactions

Problem: Your transaction on Uniswap fails and shows an error message or a “Transaction failed” alert.

Solutions:

1.Insufficient Gas Fees: Increase the gas limit or gas price to ensure your transaction is processed by the Ethereum network.

Go to your wallet settings, find “Gas” or “Transaction fees,” and manually increase the gas price.

2.Slippage Tolerance: Adjust the slippage tolerance if there’s price fluctuation.

In Uniswap, click on the gear icon and adjust the slippage tolerance. For volatile tokens, increase it to 2-5%.

3.Liquidity Issues: Sometimes, liquidity isn’t sufficient for the trade you’re trying to make.

Check if the liquidity pool for the pair you are swapping has enough liquidity, or try a smaller transaction.

4.Check Network Congestion: Ethereum can become congested, slowing transaction times.

Use a gas tracker like ETH Gas Station to choose a better time for your transaction.

2. Stuck or Pending Transactions Problem: Your transaction is stuck in a pending state for an extended period.

Solutions:

1.Cancel Transaction: If a transaction is stuck, you can try to cancel it: In your wallet, find the pending transaction and choose the option to cancel. You may need to increase the gas price to ensure it cancels quickly.

2.Speed Up Transaction: Increase the gas fee to push through the pending transaction.

Use the “Speed Up” feature in your wallet to increase gas fees and process the transaction faster.

3.Wait for Network to Clear: Sometimes, simply waiting is the best option. If the network is congested, it may take longer for your transaction to complete.

3. Insufficient Liquidity Problem: You’re trying to trade but encounter an “Insufficient liquidity” message.

Solutions:

1.Check Liquidity Pools: Verify whether the trading pair has enough liquidity. You can check liquidity by going to Uniswap Info and looking at the liquidity for your desired token pair.

2.Use Smaller Amounts: If the pool is low in liquidity, try swapping a smaller amount.

3.Switch to a Different Pool: If one liquidity pool lacks sufficient liquidity, consider finding another one with more supply.

4. Slippage Tolerance Errors Problem: You encounter an error due to high slippage or volatility in token price.

Solutions:

1.Adjust Slippage Tolerance: Increase slippage tolerance in the Uniswap settings.

Click the gear icon in the swap interface and adjust the tolerance to 2-5%. Be cautious of high slippage, as it can result in less favorable prices.

2.Trade During Low Volatility: Wait for times of lower volatility or use a stable token to avoid drastic price fluctuations.

5. Token Not Displaying in Wallet Problem: After a successful trade, your newly swapped tokens are not showing up in your wallet.

Solutions:

1.Add the Token Manually: If your wallet doesn’t recognize a token, you’ll need to manually add the token contract address.

Find the token’s contract address on Etherscan or Uniswap Info, then go to your wallet and add it using this address.

2.Check on Etherscan: Verify the token transfer was successful by looking up your wallet address on Etherscan.

6. Gas Fees Too High Problem: Ethereum network gas fees are too expensive to perform swaps.

Solutions:

1.Check Gas Prices: Use ETH Gas Station to track gas prices and find a more optimal time for transactions.

2.Consider Layer 2 Solutions: Consider using a Layer 2 scaling solution like Arbitrum or Optimism, which Uniswap supports, for lower fees.

3.Use a Different Time of Day: Gas prices can fluctuate based on network demand. Off-peak hours often have lower fees.

7. Price Impact Too High Problem: You get an error or warning about high price impact during a swap.

Solutions:

1.Break the Trade into Smaller Amounts: If you're trading a large amount, the price impact might be significant.

Break your trade into smaller chunks to reduce price impact.

2.Check Liquidity: Low liquidity in a pool can lead to high price impact.

Check if a different liquidity pool for the same tokens has more liquidity.

8. Uniswap Interface Not Loading Properly Problem: The Uniswap interface is not loading or showing errors.

Solutions:

1.Clear Cache and Cookies: Sometimes, browser cache or cookies can interfere with the Uniswap interface. Clear your browser’s cache and cookies.

2.Use a Different Browser: Try switching browsers or using incognito mode to see if the issue persists.

3.Check Ethereum Network: Make sure that the Ethereum network (or any connected Layer 2 solution like Arbitrum) is online and not having outages.

9. Issues with Token Approval Problem: You’re unable to approve a token for swapping on Uniswap.

Solutions:

1.Revoke Previous Approvals: Use a service like Etherscan Token Approval Checker to revoke previous token approvals and retry.

2.Retry Approval with Higher Gas: Increase the gas fee for token approval to ensure the transaction gets processed.

10. Wallet Not Connecting to Uniswap Problem: Your wallet (e.g., MetaMask) doesn’t connect or sync properly with Uniswap.

Solutions:

1.Check Wallet Network: Ensure your wallet is connected to the Ethereum mainnet or a compatible Layer 2 network like Optimism or Arbitrum.

2.Reconnect Wallet: Try disconnecting and reconnecting your wallet to Uniswap by refreshing the page and reconnecting from the Uniswap interface.

3.Check Browser Extensions: Some browser extensions may interfere with wallet connections. Disable any ad blockers or privacy tools and try again.

Conclusion

These are the most common issues users face on Uniswap, along with solutions that can help you resolve them. If problems persist, check the Uniswap Help Center or community forums for further support. Always ensure you’re using the correct URLs and wallet addresses to avoid scams.

How Uniswap Works?

The Uniswap protocol does things differently to centralized exchanges. Its open-source software has been built on the Ethereum blockchain — and allows users to trade ERC-20 tokens without the need for a middleman. As well as helping to reduce fees, this can iron out some thorny issues concerning censorship. Liquidity providers play a big part in making everything happen without the need for an order book. Anyone can get involved in these liquidity pools as long as they contribute the equivalent value of two tokens, such as ETH and stablecoins such as USDT or DAI. In exchange, they'll get liquidity pool tokens that can then be used on other decentralized apps. This also ensures that they can get their contribution back at any time.

Users pay transaction fees whenever they complete a swap using a trading pair, and a portion of this goes to the liquidity provider based on how many pool tokens they own.

A Step-by-Step Guide to Using UniSwap

So, how do you swap tokens on Uniswap? Here is a straightforward guide:

1. Go to the Uniswap app.

2. Connect an Ethereum wallet such as MetaMask[etc].

3. Select the token you'd like to convert in a dropdown menu, and the cryptocurrency you'd like to swap it for.

4. After clicking "Swap," preview the transaction in a pop-up window and then confirm the request directly from your wallet.

5. Next, you'll have to wait a little while for the transaction to be finalized on the Ethereum blockchain — and remember that you can keep track of how this is progressing through the Etherscan.io blockchain explorer.

Future Trends and Developments for Uniswap

In this section, we delve into the prospective directions and advancements awaiting Uniswap in the dynamic landscape of decentralized finance (DeFi). As one of the pioneering decentralized exchanges (DEXs), Uniswap has already made significant strides in revolutionizing how users trade and provide liquidity in the cryptocurrency realm. However, the journey of innovation is far from over, and the future holds exciting possibilities for Uniswap’s evolution and adaptation.

The Evolution of Automated Market Making (AMM)

One of the forefront trends for Uniswap lies in the continuous refinement and enhancement of its automated market making (AMM) protocol. As the DeFi space matures and user demands evolve, Uniswap is poised to introduce advanced algorithms and mechanisms to optimize liquidity provision, minimize slippage, and enhance overall trading efficiency. Expect to witness the integration of cutting-edge technologies such as machine learning and algorithmic trading strategies to further bolster Uniswap’s AMM capabilities.

Interoperability and Cross-Chain Compatibility

Another significant aspect of Uniswap’s future trajectory involves its interoperability and cross-chain compatibility initiatives. As blockchain interoperability becomes increasingly crucial in fostering a connected and seamless DeFi ecosystem, Uniswap is anticipated to explore integrations with various blockchain networks beyond Ethereum. This expansion opens doors to a broader range of assets, liquidity pools, and user bases, thereby solidifying Uniswap’s position as a pivotal hub for decentralized exchange across multiple blockchains.

Regulatory Compliance and Governance Framework

Amidst the evolving regulatory landscape surrounding cryptocurrencies and DeFi platforms, Uniswap is poised to navigate the complexities of compliance while preserving its decentralized ethos. Anticipate the development of robust governance frameworks and compliance protocols within the Uniswap ecosystem, fostering transparency, accountability, and regulatory adherence. Additionally, community-driven governance mechanisms are expected to flourish, empowering Uniswap token holders to actively participate in decision-making processes and shape the platform’s future direction.

Integration of Layer 2 Scaling Solutions

Scalability remains a critical challenge for decentralized exchanges, particularly in the face of surging transaction volumes and network congestion. To address this issue, Uniswap is likely to explore the integration of layer 2 scaling solutions such as Optimistic Rollups and zk-rollups. By leveraging off-chain scaling techniques while retaining the security guarantees of the Ethereum blockchain, Uniswap can significantly enhance throughput, reduce gas fees, and improve the overall user experience, paving the way for mass adoption and scalability.

Conclusion

In conclusion, the future of Uniswap is brimming with innovation, collaboration, and adaptability. By embracing emerging trends, fostering interoperability, navigating regulatory landscapes, and prioritizing scalability, Uniswap is primed to redefine the decentralized exchange space and catalyze the broader adoption of DeFi principles. As we embark on this journey of evolution and progress, Uniswap remains at the forefront of pioneering change and shaping the future of decentralized finance.

The Unique Features of Uniswap exchange

When delving into the realm of decentralized finance (DeFi), one cannot overlook the distinctive features that set Uniswap apart from traditional exchanges. At the heart of its design lies a revolutionary concept that empowers users with unparalleled control over their assets and trading experience.

Uniswap operates on the principle of automated liquidity provision through the use of smart contracts, eliminating the need for order books and centralized intermediaries. This groundbreaking approach not only ensures continuous liquidity but also fosters a more transparent and efficient trading environment.

Constant Product Market Maker Mechanism: Uniswap’s unique trading mechanism relies on a constant product formula, where the product of the quantities of two tokens in a liquidity pool remains constant. This algorithmic approach dynamically adjusts token prices based on supply and demand, enabling seamless token swaps without the need for counterparties.

Permissionless Listing: Unlike traditional exchanges that require rigorous vetting processes for token listings, Uniswap allows anyone to create a liquidity pool for any ERC-20 token, thereby democratizing access to the trading market. This permissionless nature fosters innovation and enables the long tail of assets to thrive within the DeFi ecosystem.

Decentralized Governance: Uniswap operates as a decentralized autonomous organization (DAO), empowering token holders to actively participate in protocol governance. Through community-driven proposals and voting mechanisms, users have a direct say in shaping the future direction of the platform, ensuring its continued relevance and adaptability.

Immutable Smart Contracts: Smart contracts deployed on the Ethereum blockchain govern Uniswap’s operations, providing users with a high degree of security and trustlessness. Once deployed, these contracts are immutable, meaning they cannot be altered or tampered with, ensuring the integrity and reliability of the platform.

As users navigate the intricacies of Uniswap, they are greeted with a paradigm shift in the way trading is conducted–a shift towards decentralization, transparency, and user empowerment.

Frequently Asked Questions about the Uniswap App Terms of Service.

Periodically, we update our Terms of Service as we work to improve the Uniswap App user experience. We want our users to understand exactly what’s contained in updates and why we’ve made those updates.

Q.What is Uniswap Exchange?

A.Uniswap Exchange is a decentralized finance (DeFi) protocol that enables automated token exchange on the Ethereum blockchain. It allows users to swap ERC-20 tokens without the need for an order book or centralized intermediaries.

Q.How does Uniswap work?

A.Uniswap uses a unique automated market maker (AMM) system where trades are executed directly against liquidity pools rather than through an order book. Users can swap tokens by providing liquidity to these pools, earning fees in return.

Q.What are the benefits of using Uniswap?

A.Using Uniswap offers several benefits, including decentralized trading, lower fees compared to traditional exchanges, 24/7 availability, and the ability to easily list new tokens without requiring approval from a central authority.

Q.Is Uniswap safe to use?

A.Uniswap has gained popularity, but users should exercise caution as with any decentralized platform. While it provides benefits like non-custodial trading, there are risks such as impermanent loss for liquidity providers and the potential for smart contract vulnerabilities.

Q.How can I participate in Uniswap?

A.To participate in Uniswap, you can connect your Ethereum wallet to the platform and start swapping tokens or providing liquidity to pools. Make sure to research and understand the risks involved, and consider factors like gas fees and token prices before trading.

Q.What is Uniswap Exchange?

A.Uniswap Exchange is a decentralized cryptocurrency exchange protocol built on the Ethereum blockchain. It allows users to swap various ERC-20 tokens directly from their wallets without the need for intermediaries or order books.

Q. What are the major changes in the October 25, 2021 Updated Terms of Service?

A. Uniswap Labs is committed to developing products in a way that provides a safe, transparent, and robust financial infrastructure that can empower users around the world. In line with that commitment, we are beginning to implement a new risk-management system that assesses the risk associated with each Ethereum address that interacts with app.uniswap.org.

Q. What kind of risk are you hoping to assess?

A. With the help of TRM Labs, a blockchain intelligence service provider, we're assessing the risk presented by wallet addresses that interact with the Uniswap Labs app in order to apply an industry-wide standard of categories of risk (e.g., addresses associated with ransomware or stolen funds). The initial assessment will help us understand how the Uniswap Labs app is being used and respond as needed, while maximizing user privacy.

Q. What data is collected in this process?

A. The only new data that will be collected and analyzed are the wallet address of users connecting to the Uniswap Labs app and the transaction signature and hash of any submitted transactions. No other user data will be collected as part of this initial monitoring process. Users will not be identified in this risk-assessment process.

Q. Will this risk-assessment impact access to the Uniswap Protocol through other interfaces?

A. No. Only the Ethereum addresses interacting with the Uniswap Labs app deployment will be cross-checked against standards for risk assessment. This includes app.uniswap.org and the IPFS build published by Uniswap Labs. We will not be monitoring the addresses of those interacting with the underlying Uniswap Protocol via other interfaces. Given the Protocol’s decentralized and open-source nature, we do not control users’ access to it via any portal other than our own app.

Q: What other APIs/data services does the Uniswap Labs Interface use?

A: The Uniswap Labs app also uses the Infura API, The Graph API, and Google Analytics. The Infura API allows us to fetch user balances and market prices from the Ethereum network. The Graph API is used to obtain market data such as liquidity distribution of a pool. Google Analytics is used to learn more about user behavior and improve the user experience. We do not use cookies for Google Analytics.

Common Errors.

This document covers a few error codes frequently encountered while building on Uniswap V2.

UniswapV2: K

This is an error that is frequently encountered, and requires a bit of context to understand it.

The Uniswap constant product formula is “X * Y = K”. Where X and Y represent the respective reserve balances of two ERC-20 tokens, and “K” represents the product of the reserves. It is this “K” to which the “K” error refers.

In essence, the “K” error means that a trade was attempted that somehow left the trading pair with less reserves than should be there, and as a result the transaction is reverted.

This can have a few different causes.

Fee On Transfer Tokens

The most common examples are caused by “fee on transfer” tokens.

Inclusive Fee On Transfer Tokens

In most cases, a fee on transfer token burns or diverts a small portion of every transfer such that the recipient of the transfer ends up with slightly less than the sender gave. This is called an “inclusive” fee on transfer.

In the case of inclusive fee on transfer tokens, you can use the corresponding swap functions in the router contract which end with “SupportingFeeOnTransfer”. These functions succeed by adjusting the “amountOutMin” parameter to check the recipient amount rather than the sending amount when calculating the invariant.

Exclusive Fee On Transfer Tokens

The other type, “exclusive” fee on transfer tokens, work by sending an additional transfer from the sending address after the primary transfer. Because the router contract cannot anticipate this trailing transfer when calculating the invariant, the transaction will either revert, or partially succeed by sending the primary transfer but breaking the pool upon the trailing transfer.

In the case of exclusive fee on transfer tokens, the SupportingFeeOnTransfer functions may work, but there will be some tokens designed in such a way that they fundamentally break the router. If you are still getting a “K” error when using these functions, you may need to make a fork of the router contract that accommodates your token design.

Rebasing Tokens

The less common instance of the “K” error is as a result of rebasing tokens.

Rebasing tokens can alter the balance of any addresses holding their tokens arbitrarily. This usually works at pre specified intervals and as a result of a handful of variables used in the economics of a rebasing token.

Rebasing tokens typically work in two ways.

Negative Rebasing Tokens

A negative rebasing token, the more common variant, deflates the balances of token owners. Because the rebasing is not triggered by transfers, the router cannot expect when or how a rebasing will happen. Once it does, the pair reserves will be unbalanced, and the next person to transact with the pair will bear the cost of the delta as a result of the rebasing.

Needless to say, an unenviable position.

Negative rebasing tokens have solved this error by altering their token contract to call sync on the trading pair at the end of every transaction involving the Uniswap router contract. Those interested in forking the router contract should anticipate that negative rebasing tokens will break the pair until the token contracts are updated to accommodate your new router.

Positive Rebasing Tokens

Positive rebasing tokens arbitrarily increase the balances of token holders. When a positive rebase happens, it creates a surplus that is unaccounted for in the trading pair. Because the extra tokens are unaccounted for in the trading pair, anyone can call skim() on the trading pair and effectively steal the positive difference from the rebalance.

While positive rebalancing does not break any functionality of Uniswap, those interested in them should be aware that the positive balance found in any pair will be freely available for taking.

A Note on Rebasing Tokens

For those interested in building a rebasing token, a word of caution: many contracts involving decentralized trading and liquidity provisioning will break upon interacting with your token. An example approach that will lead to much easier integration in future protocols can be found in CHAI. CHAI uses a wrapper function that contains the rebalancing within the wrapper, such that the redeemable token can be easily integrated into many different systems.

UniswapV2: LOCKED

The LOCKED error is a guard built into the router contract that prevents customized reentrancy contracts from attempting to return malicious code into the router contract at the end of a transaction.

This error is commonly encountered when using Ganache CLI to fork the Ethereum mainnet to a local instance as a part of a development environment. The error is a bug in Ganache-Cli that will hopefully be fixed in a future release by the truffle team.

A temporary fix is available by simply restarting the local fork.

No Access To Archive Node

This is an error with either Metamask or Ganache-CLI. It usually occurs after a local fork is instantiated and contracts are deployed but there is one failed transaction.

A temporary fix is available by restarting the local fork and resetting metamask.

UniswapV2: TRANSFER_FAILED

This means the core contract was unable to send tokens to the recipient. This is most likely due to a scam token, where the token owner has maliciously disabled the transfer function in a way that allows users to buy the token, but not sell them.

UniswapV2: EXPIRED

This is a result of a transaction that took too long to be broadcast to the mainnet.

Uniswap does not set gas prices natively, so most users default to the suggested gas prices in metamask. Sometimes metamask gets it wrong, though, and sets the gas price too low. If a swap takes more than 20 minutes to execute, the core contract won’t allow it to go through.

Action Requires an Active Reserve

VM Exception While Processing Transaction: Action Requires an Active Reserve

This is potentially a ganache bug encountered when working on flash swaps. We haven't figured out the source of it yet.

Unable To Approve Transaction On The Front End

There are rare circumstances where users are unable to approve a token on the Uniswap front end.

This is a result of some token contracts taking steps to defend against malicious contracts that attempt to front run approvals and steal a users tokens. It happens only when the user is trying to increase an approval allowance from a preallocated amount to a larger one, and only happens with a few token contracts.

The solution is have the user manually set the router contract approval amount to zero, then to the number they want. The easiest way to do this is through Etherscan.