@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 
bool use_split_keypool = set_pre_split_keypool.empty();
        std::set<int64_t>& setKeyPool = use_split_keypool ? (fReturningInternal ? setInternalKeyPool : setExternalKeyPool) : set_pre_split_keypool;
        
        if (setKeyPool.empty()) {
            return false;
        }
        WalletBatch batch(*database);
        auto it = setKeyPool.begin();
        nIndex = *it;
        setKeyPool.erase(it);
        if (!batch.ReadPool(nIndex, keypool)) {
            throw std::runtime_error(std::string(__func__) + ": read failed");
        }
        if (!HaveKey(keypool.vchPubKey.GetID())) {
            throw std::runtime_error(std::string(__func__) + ": unknown key in key pool");
        }
        
        if (use_split_keypool && keypool.fInternal != fReturningInternal) {
            throw std::runtime_error(std::string(__func__) + ": keypool entry misclassified");
        }
        if (!keypool.vchPubKey.IsValid()) {
            throw std::runtime_error(std::string(__func__) + ": keypool entry invalid");
        }
        m_pool_key_to_index.erase(keypool.vchPubKey.GetID());
        WalletLogPrintf("keypool reserve %d\n", nIndex);
    }
    NotifyCanGetAddressesChanged();
    return true;
}
void CWallet::KeepKey(int64_t nIndex)