Bitcoin core's estimatesmartfee error "Insufficient data or no feerate found" with synced node I'm running bitcoin core version 0.17.0 on the Testnet and since yesterday, I've been experiencing problems with the RPC estimatesmartfee. I'm getting as a response: 


  "errors": "Insufficient data or no feerate found"


The output of getblockcount is 1434922, which complies with that number of blocks on block explorers.

getnetworkinfo says I've got 8 peers connected.

I believe my node is fully synced, and, in fact, I just made a transaction while I'm writing this.

What might be the issue here? I pasted the final lines of the debug.log here.
The fee estimation is completely based on how long your node has been running, how many transactions have entered the mempool, and how many of those transactions have been confirmed. It is not (and cannot be) based on the fee information of transactions already included in blocks. So it does not matter whether you are fully synced or not. If you just started up or if there are few transactions being confirmed, then the fee estimation will not have enough data to work.

Testnet does not have a lot of traffic, and AFAIK, a miner is currently not including any transactions in their blocks. Thus there is not a lot of information available for fee estimation to work, so it does not. That is why it is currently unavailable.