@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 
}.ToString());
    std::string strLabel;
    if (!request.params[1].isNull())
        strLabel = request.params[1].get_str();
    
    bool fRescan = true;
    if (!request.params[2].isNull())
        fRescan = request.params[2].get_bool();
    if (fRescan && fPruneMode)
        throw JSONRPCError(RPC_WALLET_ERROR, "Rescan is disabled in pruned mode");
    WalletRescanReserver reserver(pwallet);
    if (fRescan && !reserver.reserve()) {
        throw JSONRPCError(RPC_WALLET_ERROR, "Wallet is currently rescanning. Abort existing rescan or wait.");
    }
    if (!IsHex(request.params[0].get_str()))
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey must be a hex string");
    std::vector<unsigned char> data(ParseHex(request.params[0].get_str()));
    CPubKey pubKey(data.begin(), data.end());
    if (!pubKey.IsFullyValid())
        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Pubkey is not a valid public key");
    {
        auto locked_chain = pwallet->chain().lock();
        LOCK(pwallet->cs_wallet);
        for (const auto& dest : GetAllDestinationsForKey(pubKey)) {
            ImportAddress(pwallet, dest, strLabel);
        }
        ImportScript(pwallet, GetScriptForRawPubKey(pubKey), strLabel, false);
        pwallet->LearnAllRelatedScripts(pubKey);
    }
    if (fRescan)