@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 
{
    WalletBatch batch(*database);
    batch.WriteBestBlock(loc);
}
void CWallet::SetMinVersion(enum WalletFeature nVersion, WalletBatch* batch_in, bool fExplicit)
{
    LOCK(cs_wallet); 
    if (nWalletVersion >= nVersion)
        return;
    
    if (fExplicit && nVersion > nWalletMaxVersion)
            nVersion = FEATURE_LATEST;
    nWalletVersion = nVersion;
    if (nVersion > nWalletMaxVersion)
        nWalletMaxVersion = nVersion;
    {
        WalletBatch* batch = batch_in ? batch_in : new WalletBatch(*database);
        if (nWalletVersion > 40000)
            batch->WriteMinVersion(nWalletVersion);
        if (!batch_in)
            delete batch;
    }
}
bool CWallet::SetMaxVersion(int nVersion)