@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 
if (!ProduceSignature(*this, MutableTransactionSignatureCreator(&txNew, nIn, coin.txout.nValue, SIGHASH_ALL), scriptPubKey, sigdata))
                {
                    strFailReason = _("Signing transaction failed");
                    return false;
                } else {
                    UpdateInput(txNew.vin.at(nIn), sigdata);
                }
                nIn++;
            }
        }
        
        tx = MakeTransactionRef(std::move(txNew));
        
        if (GetTransactionWeight(*tx) > MAX_STANDARD_TX_WEIGHT)
        {
            strFailReason = _("Transaction too large");
            return false;
        }
    }
    if (gArgs.GetBoolArg("-walletrejectlongchains", DEFAULT_WALLET_REJECT_LONG_CHAINS)) {
        
        LockPoints lp;
        CTxMemPoolEntry entry(tx, 0, 0, 0, false, 0, lp);
        CTxMemPool::setEntries setAncestors;
        size_t nLimitAncestors = gArgs.GetArg("-limitancestorcount", DEFAULT_ANCESTOR_LIMIT);
        size_t nLimitAncestorSize = gArgs.GetArg("-limitancestorsize", DEFAULT_ANCESTOR_SIZE_LIMIT)*1000;
        size_t nLimitDescendants = gArgs.GetArg("-limitdescendantcount", DEFAULT_DESCENDANT_LIMIT);
        size_t nLimitDescendantSize = gArgs.GetArg("-limitdescendantsize", DEFAULT_DESCENDANT_SIZE_LIMIT)*1000;
        std::string errString;
        LOCK(::mempool.cs);