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.
{ "sendall", 4, "replaceable"},
    { "sendall", 4, "solving_data"},
    { "simulaterawtransaction", 0, "rawtxs" },
    { "simulaterawtransaction", 1, "options" },
    { "simulaterawtransaction", 1, "include_watchonly"},
    { "importprivkey", 2, "rescan" },
    { "importaddress", 2, "rescan" },
    { "importaddress", 3, "p2sh" },
    { "importpubkey", 2, "rescan" },
    { "importmulti", 0, "requests" },
    { "importmulti", 1, "options" },
    { "importmulti", 1, "rescan" },
    { "importdescriptors", 0, "requests" },
    { "listdescriptors", 0, "private" },
    { "verifychain", 0, "checklevel" },
    { "verifychain", 1, "nblocks" },
    { "getblockstats", 0, "hash_or_height" },
    { "getblockstats", 1, "stats" },
    { "pruneblockchain", 0, "height" },
    { "keypoolrefill", 0, "newsize" },
    { "getrawmempool", 0, "verbose" },
    { "getrawmempool", 1, "mempool_sequence" },
    { "estimatesmartfee", 0, "conf_target" },
    { "estimaterawfee", 0, "conf_target" },
    { "estimaterawfee", 1, "threshold" },
    { "prioritisetransaction", 1, "dummy" },
    { "prioritisetransaction", 2, "fee_delta" },
    { "setban", 2, "bantime" },
    { "setban", 3, "absolute" },
    { "setnetworkactive", 0, "state" },