A 417 error means a transaction failed to broadcast. Usually broadcast errors are caused by doing multiple transactions at the same time.
When a transaction is created at least one UTXO is used. If a 2nd transaction is created before the 1st one finishes processing it may use one of the same UTXOs. Since a UTXO can be used once, only one of the transactions can be valid. Usually the 1st one will finish processing first and the 2nd transaction will give a 417 error.
In some instances both transactions will get broadcast and the wrong one will get processed by Memo servers first. When this happens, an incorrect UTXO can be saved. Once a bad UTXO is saved any transaction created with it will fail and give a 417 error. Usually this will clear up when the next block is processed and the discrepancy is resolved.
Although rare, sometimes a bad UTXO will remain in the system for longer periods of time. When this happens your balance on Memo will usually not match other block explorers. This can result in frequent 417 errors with any transaction that tries to use those UTXOs.
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