Context
I created a transaction (using the full balance of an output) with the Bitcoin Core Wallet (running as full node). The transaction got into the mempool of major nodes, as expected. I set the fee to what the client recommended for a slow transaction (little more than 9 sat/B) , but these days this turns out to be very low. Given the current state of the mempool at hoenicke this may get confirmation in weeks, if at all.
Increasing the fee fails
I initially, deliberately, set the transaction to "Request Replace-By-Fee", and I want do increase the fee now. I expected to take some part of the "target amount" and use it as fee, leaving the total amount of the transaction the same (still spending the complete output in total)
However, this does not seem to be possible by design. I get a "Fee bump error" saying "Increasing the transaction fee failed (Transaction does not have a change output)".
What to do about it?
Why am I not able to change the target/fee balance of a transaction, and how am I expected to increase the fee at this point?
Transaction Details (as per Request)
Summary
Size 1xx (bytes)
Weight 7xx
Lock Time Block: 49xxxx
Inputs and Outputs
Total Input 0.01xxxxxx BTC
Total Output 0.01xxxxxx BTC
Fees 0.00001xxx BTC
Fee per byte 9.xxx sat/B
Fee per weight unit 2.xxx sat/WU
Estimated BTC Transacted 0.019xxxxx BTC
Both input and output addresses start with "1"