Current bitcoin-master on testnet, `maxconnections=8` in the config file. Running in VM that doesn't have public IP and is not reachable from the Internet.

Wait until you have 8 peers.

```
telnet localhost 18333
```

It will result in:

```
Assertion failed: (nMaxInbound > 0), function AcceptConnection, file net.cpp, line 973.
```

First found in https://github.com/bitcoin/bitcoin/pull/8996, but can be reproduced on master.

int64_t nStart = GetTimeMillis();
    {
        CAddrDB adb;
        if (adb.Read(addrman))
            LogPrintf("Loaded %i addresses from peers.dat  %dms\n", addrman.size(), GetTimeMillis() - nStart);
        else {
            addrman.Clear(); 
            LogPrintf("Invalid or missing peers.dat; recreating\n");
            DumpAddresses();
        }
    }
    if (clientInterface)
        clientInterface->InitMessage(_("Loading banlist..."));
    
    nStart = GetTimeMillis();
    CBanDB bandb;
    banmap_t banmap;
    if (bandb.Read(banmap)) {
        SetBanned(banmap); 
        SetBannedSetDirty(false); 
        SweepBanned(); 
        LogPrint("net", "Loaded %d banned node ips/subnets from banlist.dat  %dms\n",
            banmap.size(), GetTimeMillis() - nStart);
    } else {
        LogPrintf("Invalid or missing banlist.dat; recreating\n");
        SetBannedSetDirty(true); 
        DumpBanlist();
    }
    uiInterface.InitMessage(_("Starting network threads..."));
    fAddressesInitialized = true;