Wallet: Reenable -fallbackfee by default for regtest and signet (and maybe testnet too)? #20087

This PR merged in October 2019 disabled -fallbackfee by default across all chains (mainnet, testnet, regtest).

The only motivation for doing this for regtest (and maybe testnet too) that I can see is:

Now it is 0 by default for all chains, thus there's no need to call Params(). (comment)

However, this does mean that if you don't set a fee or enable -fallbackfee you get this error.

error code: -4
error message:
Fee estimation failed. Fallbackfee is disabled. Wait a few blocks or enable -fallbackfee.

Any thoughts on reenabling -fallbackfee by default for regtest, signet (and maybe testnet too)? I think it makes sense to continue to have it disabled by default for real money on mainnet.

If I'm missing context please direct me to it and I'll close this.

Bitcoin StackExchange post: https://bitcoin.stackexchange.com/questions/97174/when-using-bitcoin-cli-i-get-an-error-regarding-fallback-fees-when-trying-to-sen

No strong opinion, but I have a slight preference to keep it the way it is. If documentation is missing, then it should be improved. The error message could probably be updated on how to set a feerate over RPC, not just the startup setting, which would require a restart of the server.

So an extended error message, something like:

Fee estimation failed and -fallbackfee is disabled. Enable -fallbackfee (requires restart), wait a few blocks or manually set a fee as an additional argument to your bitcoin-cli command e.g. 1 sat/B

You don't want too long error messages right?

You don't want too long error messages right?

Right. Maybe it is time to explain Bitcoin Core fee estimation/fee settings to users in one document and refer to that in the error message?

Yeah I think the above is the best approach longer term. I'll close this for now. Thanks

Heh, this is still something that should be addressed. ;)

Ok I'm happy for this to be a good first issue or to do it myself.

For now here are some resources that will be useful.

• How Bitcoin Core estimates transaction fee (StackExchange)
• Bitcoin Code code documentation on BlockPolicyEstimator
• The fallback fee error (StackExchange)
• Opt in RBF FAQ on bitcoincore.org

Presumably you mean something like this PSBT doc but for fee estimation/fee settings. And stored in the doc directory.

The issue didn't seem to attract much attention in the past. Also, the issue seems not important enough right now to keep it sitting around idle in the list of open issues.

Closing due to lack of interest and direction. Pull requests with improvements are always welcome.