How to fix pending transaction on Ethereum ??

Ethereum operates on something called Nonce which means “order of transaction lowest Nonce always goes first”. So even if you sent another transaction with higher gas it will stuck. All you need to do is find the transaction with the lowest gas fee which cause the problem. Copy your own address and paste it in Etherscan. Go to the transaction which got stuck with status Pending, check the nonce number. For example nonce is number 7, go to your Metamask wallet settings, click “Advance”, scroll down and you will see something like “Customize transaction nonce” make sure this is on. Next what you have to do is send the transaction with 0 Eth to yourself (it will cost you a little bit of gas but it will fix the problem). Click the “Send” button, paste your own eth address, put the correct gas price (check here: Gas Tracker) and click “Next”. After that you will see the option “Custom Nonce”. You have to put the number of nonce you have in the stuck transaction (in this case is number 7). Just type-in the number 7 and click “Confirm”. This will fix your pending transaction and will push the other transactions you made after this. If you have any more questions don’t hesitate to ask.

It is very annoying when your transaction has a pending status for tens of minutes and you need to complete the transfer very quickly. Unfortunately, Ethereum does not provide a cancel button. You have to deal with it in a different way. A very simple way. Just overwrite the transaction, setting it at least 10% higher Gas than before. If the transaction has already fallen into the transaction field, it has been given certain nonce values and addresses you have entered. It is identified and unique based on these values. Because of this, we can resend the transaction with the same parameters, only changing the GWEI value. Namely, if your first transaction was sent with GWEI = 4, then now resend that transaction, to the same address and the same ETH amount, but change the GWEI to e.g. the preferred GWEI = 21. This should overwrite the transaction that falls into the transaction field and is caught by the miner quickly. If a transaction with a higher GWEI is caught, then the one with the lower GWEI will cease to exist because they have the same Nonce and the more profitable one has already been mined in the specified block.

I don't know about ETH, but I know how it is with Bitocin, so I will explain maybe it will help you.
This situation can happen to anyone who has set the transaction commission too low. However, you don't have to worry that the funds in bitcoin have been permanently blocked and did not reach the address we sent. How to deal with such a situation? However, several things we can do, but they need to be taken in the right order.

If you have patience and can wait, wait 72 hours. Why so long? Because during this time, unconfirmed transactions will go to the so-called mempool - such a waiting room for transactions. It is maintained by each bitcoin node. Usually transactions are removed from mempool up to 3 days if they are still unconfirmed. If your transaction does not go through during this time, it will be removed and the funds will come back to you.

Replace by Fee - change an unconfirmed transaction to another one

You may also use the Replace by Fee option, which consists in exchanging an unconfirmed transaction in the waiting room (mempool) for another one, which has a higher commission and at least one input (common entrance). This will allow you to conduct your trade by setting the fee too low. The option is available in most wallets, including Samourai Wallet and Green Bitcoin Wallet.

 Transaction accelerators

If you want to pay extra, use the free payment gas accelerators. You need to enter your transaction ID in it. It works by using a specific number of nodes to get your transaction back into the mempool. This may help you, although a more efficient method is replace by fee. If you decide to use free accelerators, you should not accelerate an unapproved transaction too often. You should do it every few hours or so. At the moment I recommend you a good service like bitaccelerate.com.

Well, in this case, there are several options:

Wait until processing a transaction with such a fee against the others at Mempool is attractive to miners. However, it might as well be cancelled after a few days and return to the original address.
The ViaBTC mine has provided a tool on its website to speed up the joining of transactions to the block. If the fee was extremely low then this system will also reject the processing as not worthwhile.
If you were using an updated Electrum wallet then it is possible that you had the Replace-by-fee option set in your preferences and you can then, say, "update" your transfer so that it has the appropriate transaction fee.
If you feel up to it, some people advise copying your wallet to manually remove the transaction that is stuck in order to try sending it again. However, this is a process that requires knowledge of how the wallet is structured.
The "Child Pays For Parent" method (CPFP) is a way in which the recipient increases the fee of the transfer going to them. This is a significant difference from RBF because there the sender updated the transfer.

As a last resort, you can use a method to push our unconfirmed transaction called Child Pays for Parent. This method involves making another transaction that has a higher transaction fee set, so that the miners spread it between the two transactions and thus also approve the earlier one that got stuck. How it works. The method is to execute another trade using the UTXO (output) from the one that is unconfirmed. This means that in order for the miners to confirm the child transaction, they must first attach the parent transaction to the block that previously had too low a fee. Chil Pays for Parent is also available in most notable wallets as a default solution.

Basically, all leading wallets nowadays suggest the optimal transaction commissions themselves based on the current situation in the network, so it is worth taking advantage of these facilities.