Quote from: ETFbitcoin on February 19, 2021, 10:04:51 AM

Also ensure the transaction fee rate at least 1 sat/vbyte, because AFAIK Bitcoin Core also shows same error if transaction fee rate at least 1 sat/vbyte.

It isn't a "min relay" error... it is "mempool min fee"... because of the huge size of the mempool... transactions that are extremely far away from the tip get purged (I believe the idea is that you no longer have to wait 14 days for the transaction to get "dropped" if there is literally 0% chance of your transaction getting confirmed within that timeframe and also to keep the mempool memory usage size under control).

The 2 places I know of that give an indication of what the "mempool min fee" likely to being currently used by default nodes are:
mempool.space:

Check the "purging" value... currently any transaction with less than a fee rate of 6.5 sats/vbyte will likely be removed from a (default configured) node to try and keep the mempool memory usage down at the 300MB range.

or, statoshi.info:

The bottom graph on the "Memory Pool" page shows the "mempool min fee" rate...