Why are polygon transactions being dropped and replaced?

Question

It seems transactions on polygon can get automatically dropped and replaced.

original: 0xa67609bacf51ab83b1989e4097b4147574b4e26399bec636c4cfc5e12dfa2897 replaced: 0xec0d501619b5fc9cde6af41df929eeded252138a49965f15a7598bf2e532e555

What is happening here?

On Ethereum, I believe this can only happy if someone proactively replaces the tx by submitting another with the same nonce and higher gas price. Is that correct?

{"level":"error","message":"Error: transaction was replaced [ See: https://links.ethers.org/v5-errors-TRANSACTION_REPLACED ] (cancelled=true, reason=\"replaced\", replacement={\"hash\":\"0xec0d501619b5fc9cde6af41df929eeded252138a49965f15a7598bf2e532e555\",\"type\":2,\"accessList\":[],\"blockHash\":\"0x252f663dfb64dd82dff77b5e4fbe2073cd77248c5ce8dff1191c87ac22d97cf9\",\"blockNumber\":39285028,\"transactionIndex\":60,\"confirmations\":2,\"from\":\"0x90Be1Ef5EEa48f1d33e2574a73E50D208bB3680E\",\"gasPrice\":{\"type\":\"BigNumber\",\"hex\":\"0x6cdbaaf8e5\"},\"maxPriorityFeePerGas\":{\"type\":\"BigNumber\",\"hex\":\"0x6cdbaaf8e5\"},\"maxFeePerGas\":{\"type\":\"BigNumber\",\"hex\":\"0x6cdbaaf8e5\"},\"gasLimit\":{\"type\":\"BigNumber\",\"hex\":\"0x0186a0\"},\"to\":\"0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174\",\"value\":{\"type\":\"BigNumber\",\"hex\":\"0x00\"},\"nonce\":112,\"data\":\"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\",\"r\":\"0x2503d5645a7620c94678ef0a5de4bca4e03b18943cec0511d58b7e444412b467\",\"s\":\"0x72c2cf739e2bfeb8335faab2c4b87b7b0464c9681a488456fa7c8fe25aef89c6\",\"v\":1,\"creates\":null,\"chainId\":137}, hash=\"0xa67609bacf51ab83b1989e4097b4147574b4e26399bec636c4cfc5e12dfa2897\", receipt={\"to\":\"0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174\",\"from\":\"0x90Be1Ef5EEa48f1d33e2574a73E50D208bB3680E\",\"contractAddress\":null,\"transactionIndex\":60,\"gasUsed\":{\"type\":\"BigNumber\",\"hex\":\"0x0110bc\"},\"logsBloom\":\"0x00000000000000001000000000000000000000000000000000000000000000000000000000000000020000000000000000008000000000000000000200000000000000000000000000000008000000800000000000000000000100000000000000000000000000000000000000000000020000000000000180000010000000000001000000400000000000008000000000008000000000004000000000000000200000000000000000000000000000000004000000000000000000000000004000100002000000000081000000000000000000000000000000100000000000000000008000000000800000000000000000000000000000000000000000100000\",\"blockHash\":\"0x252f663dfb64dd82dff77b5e4fbe2073cd77248c5ce8dff1191c87ac22d97cf9\",\"transactionHash\":\"0xec0d501619b5fc9cde6af41df929eeded252138a49965f15a7598bf2e532e555\",\"logs\":[{\"transactionIndex\":60,\"blockNumber\":39285028,\"transactionHash\":\"0xec0d501619b5fc9cde6af41df929eeded252138a49965f15a7598bf2e532e555\",\"address\":\"0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174\",\"topics\":[\"0x98de503528ee59b575ef0c0a2576a82497bfc029a5685b209e9ec333479b10a5\",\"0x00000000000000000000000090be1ef5eea48f1d33e2574a73e50d208bb3680e\",\"0xc726f5f957d29df36c915d2f2816a5906bdb096a68d79abeb83102359a3c51ef\"],\"data\":\"0x\",\"logIndex\":250,\"blockHash\":\"0x252f663dfb64dd82dff77b5e4fbe2073cd77248c5ce8dff1191c87ac22d97cf9\"},{\"transactionIndex\":60,\"blockNumber\":39285028,\"transactionHash\":\"0xec0d501619b5fc9cde6af41df929eeded252138a49965f15a7598bf2e532e555\",\"address\":\"0x2791Bca1f2de4661ED88A30C99A7a9449Aa84174\",\"topics\":[\"0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef\",\"0x00000000000000000000000090be1ef5eea48f1d33e2574a73e50d208bb3680e\",\"0x00000000000000000000000090be1ef5eea48f1d33e2574a73e50d208bb3680e\"],\"data\":\"0x0000000000000000000000000000000000000000000000000000000000002710\",\"logIndex\":251,\"blockHash\":\"0x252f663dfb64dd82dff77b5e4fbe2073cd77248c5ce8dff1191c87ac22d97cf9\"},{\"transactionIndex\":60,\"blockNumber\":39285028,\"transactionHash\":\"0xec0d501619b5fc9cde6af41df929eeded252138a49965f15a7598bf2e532e555\",\"address\":\"0x0000000000000000000000000000000000001010\",\"topics\":[\"0x4dfe1bbbcf077ddc3e01291eea2d5c70c2b422b415d95645b9adcfd678cb1d63\",\"0x0000000000000000000000000000000000000000000000000000000000001010\",\"0x00000000000000000000000090be1ef5eea48f1d33e2574a73e50d208bb3680e\",\"0x000000000000000000000000e7e2cb8c81c10ff191a73fe266788c9ce62ec754\"],\"data\":\"0x00000000000000000000000000000000000000000000000000080d77c3b67cb80000000000000000000000000000000000000000000000003005ebfb86a0d1350000000000000000000000000000000000000000000003ebfb8e3e34e504eca50000000000000000000000000000000000000000000000002ffdde83c2ea547d0000000000000000000000000000000000000000000003ebfb964baca8bb695d\",\"logIndex\":252,\"blockHash\":\"0x252f663dfb64dd82dff77b5e4fbe2073cd77248c5ce8dff1191c87ac22d97cf9\"}],\"blockNumber\":39285028,\"confirmations\":2,\"cumulativeGasUsed\":{\"type\":\"BigNumber\",\"hex\":\"0x8d88d1\"},\"effectiveGasPrice\":{\"type\":\"BigNumber\",\"hex\":\"0x6cdbaaf8e5\"},\"status\":1,\"type\":2,\"byzantium\":true}, code=TRANSACTION_REPLACED, version=providers/5.7.1)"}

Answer 1

On Ethereum, I believe this can only happy if someone proactively replaces the tx by submitting another with the same nonce and higher gas price. Is that correct?

Yes, and the same is possible on Polygon and other EVM chains.

Senders can replace their transactions for multiple reasons. For example, high-frequency trading bots continuously check if their pending transactions are still likely to be profitable - and if the transaction is not going to be profitable, the bot replaces it with another one. Either with new recalculated params that they expect to be profitable or simply with transaction from/to the same address so at least they don't lose any more funds than just the gas fees.

Note: Once you send a transaction, it's impossible to drop it completely from the mempool. That's why it is sent back to the sender address.

Or sometimes transactions are replaced by regular users that specified insufficient gasPrice and want to speed up the transaction by replacing the gas price with a higher value.