@jonasschnelli wrote in #14979:
> #14573 broke < Qt5.6 compatibility due to calling the lambda version of `addAction` that was added in Qt5.6.

We currently [support](https://github.com/bitcoin/bitcoin/blob/master/doc/dependencies.md) QT >=5.2, but hardly anyone tests with that. If we make one of the Travis machines use it, we should have a better change of catching this.

See also discussion about minimum QT version in #13478 
const CCoinControl& coin_control,
        CAmount total_fee,
        std::vector<std::string>& errors,
        CAmount& old_fee,
        CAmount& new_fee,
        CMutableTransaction& mtx) override
    {
        return feebumper::CreateTransaction(&m_wallet, txid, coin_control, total_fee, errors, old_fee, new_fee, mtx) ==
               feebumper::Result::OK;
    }
    bool signBumpTransaction(CMutableTransaction& mtx) override { return feebumper::SignTransaction(&m_wallet, mtx); }
    bool commitBumpTransaction(const uint256& txid,
        CMutableTransaction&& mtx,
        std::vector<std::string>& errors,
        uint256& bumped_txid) override
    {
        return feebumper::CommitTransaction(&m_wallet, txid, std::move(mtx), errors, bumped_txid) ==
               feebumper::Result::OK;
    }
    CTransactionRef getTx(const uint256& txid) override
    {
        auto locked_chain = m_wallet.chain().lock();
        LOCK(m_wallet.cs_wallet);
        auto mi = m_wallet.mapWallet.find(txid);
        if (mi != m_wallet.mapWallet.end()) {
            return mi->second.tx;
        }
        return {};
    }
    WalletTx getWalletTx(const uint256& txid) override