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.

{
    
    
    
    boost::this_thread::interruption_point();
    if (!pszDest) {
        if (IsLocal(addrConnect) ||
            FindNode((CNetAddr)addrConnect) || IsBanned(addrConnect) ||
            FindNode(addrConnect.ToStringIPPort()))
            return false;
    } else if (FindNode(std::string(pszDest)))
        return false;
    CNode* pnode = ConnectNode(addrConnect, pszDest, fCountFailure);
    boost::this_thread::interruption_point();
    if (!pnode)
        return false;
    if (grantOutbound)
        grantOutbound->MoveTo(pnode->grantOutbound);
    pnode->fNetworkNode = true;
    if (fOneShot)
        pnode->fOneShot = true;
    if (fFeeler)
        pnode->fFeeler = true;
    return true;
}
void CConnman::ThreadMessageHandler()