If I create an RBF transaction using the Qt GUI but specify my own custom change address, bumpfee doesn't work because it claims it can't find the change address:

    "Transaction does not have a change output"

This is because none of the outputs satisfy

    pWallet->IsChange(...)

I see there's a "TODO" commented in `CWallet::IsChange()` in `src/wallet/wallet.cpp`:

    // TODO: fix handling of 'change' outputs. The assumption is that any
    // payment to a script that is ours, but is not in the address book
    // is change.

I tend to put all my addresses in the address book whether I'm going to use them as change or not. I guess if the wallet was capable of creating its own SegWit change addresses I'd stop using custom change addresses, but currently it always seems to send change to a legacy address if I don't manually specify a change address.
{ "listtransactions", 1, "count" },
    { "listtransactions", 2, "skip" },
    { "listtransactions", 3, "include_watchonly" },
    { "walletpassphrase", 1, "timeout" },
    { "getblocktemplate", 0, "template_request" },
    { "listsinceblock", 1, "target_confirmations" },
    { "listsinceblock", 2, "include_watchonly" },
    { "listsinceblock", 3, "include_removed" },
    { "listsinceblock", 4, "include_change" },
    { "sendmany", 1, "amounts" },
    { "sendmany", 2, "minconf" },
    { "sendmany", 4, "subtractfeefrom" },
    { "sendmany", 5 , "replaceable" },
    { "sendmany", 6 , "conf_target" },
    { "sendmany", 8, "fee_rate"},
    { "sendmany", 9, "verbose" },
    { "deriveaddresses", 1, "range" },
    { "scanblocks", 1, "scanobjects" },
    { "scanblocks", 2, "start_height" },
    { "scanblocks", 3, "stop_height" },
    { "scanblocks", 5, "options" },
    { "scantxoutset", 1, "scanobjects" },
    { "addmultisigaddress", 0, "nrequired" },
    { "addmultisigaddress", 1, "keys" },
    { "createmultisig", 0, "nrequired" },
    { "createmultisig", 1, "keys" },
    { "listunspent", 0, "minconf" },
    { "listunspent", 1, "maxconf" },
    { "listunspent", 2, "addresses" },
    { "listunspent", 3, "include_unsafe" },