@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 (nLoadWalletRet != DBErrors::LOAD_OK)
    {
        if (nLoadWalletRet == DBErrors::CORRUPT) {
            InitError(strprintf(_("Error loading %s: Wallet corrupted"), walletFile));
            return nullptr;
        }
        else if (nLoadWalletRet == DBErrors::NONCRITICAL_ERROR)
        {
            InitWarning(strprintf(_("Error reading %s! All keys read correctly, but transaction data"
                                         " or address book entries might be missing or incorrect."),
                walletFile));
        }
        else if (nLoadWalletRet == DBErrors::TOO_NEW) {
            InitError(strprintf(_("Error loading %s: Wallet requires newer version of %s"), walletFile, _(PACKAGE_NAME)));
            return nullptr;
        }
        else if (nLoadWalletRet == DBErrors::NEED_REWRITE)
        {
            InitError(strprintf(_("Wallet needed to be rewritten: restart %s to complete"), _(PACKAGE_NAME)));
            return nullptr;
        }
        else {
            InitError(strprintf(_("Error loading %s"), walletFile));
            return nullptr;
        }
    }
    int prev_version = walletInstance->nWalletVersion;
    if (gArgs.GetBoolArg("-upgradewallet", fFirstRun))
    {
        int nMaxVersion = gArgs.GetArg("-upgradewallet", 0);