TechnitiumSoftware/DnsServer · error · InvalidOperationException

Network group map contains an invalid network address: {netw

Error message

Network group map contains an invalid network address: {network}

What it means

Thrown while parsing the Dns64App 'networkGroupMap' JSON object. Each key is parsed with NetworkAddress.TryParse expecting a CIDR network; on failure InvalidOperationException is raised during app initialization (the Dns64 app uses InvalidOperationException, like the blocking app, for this check).

Source

Thrown at Apps/Dns64App/App.cs:78

        #endregion

        #region public

        public Task InitializeAsync(IDnsServer dnsServer, string config)
        {
            _dnsServer = dnsServer;

            using JsonDocument jsonDocument = JsonDocument.Parse(config, _jsonParseOptions);
            JsonElement jsonConfig = jsonDocument.RootElement;

            _appPreference = Convert.ToByte(jsonConfig.GetPropertyValue("appPreference", 30));

            _enableDns64 = jsonConfig.GetProperty("enableDns64").GetBoolean();

            _networkGroupMap = jsonConfig.ReadObjectAsMap("networkGroupMap", delegate (string network, JsonElement group)
            {
                if (!NetworkAddress.TryParse(network, out NetworkAddress networkAddress))
                    throw new InvalidOperationException("Network group map contains an invalid network address: " + network);

                return new Tuple<NetworkAddress, string>(networkAddress, group.GetString());
            });

            _groups = jsonConfig.ReadArrayAsMap("groups", delegate (JsonElement jsonGroup)
            {
                Group group = new Group(jsonGroup);
                return new Tuple<string, Group>(group.Name, group);
            });

            return Task.CompletedTask;
        }

        public async Task<DnsDatagram> PostProcessAsync(DnsDatagram request, IPEndPoint remoteEP, DnsTransportProtocol protocol, DnsDatagram response)
        {
            if (!_enableDns64)
                return response;

View on GitHub (pinned to d0484b6c1e)

Solutions

1. Correct the 'networkGroupMap' key in dnsApp.config to valid CIDR notation (e.g. '2001:db8::/64', '192.168.0.0/16').
2. Use '/128' or '/32' for a single host and never include a ':port'.
3. Put the NAT64 translation prefix in 'dns64PrefixMap', not in 'networkGroupMap'.

Example fix

// before (dnsApp.config)
"networkGroupMap": { "2001:db8::1": "groupA" }
// after
"networkGroupMap": { "2001:db8::/64": "groupA" }

foreach (string key in networkGroupMapKeys)
{
    if (!NetworkAddress.TryParse(key, out NetworkAddress _))
        throw new FormatException($"Dns64 'networkGroupMap' key '{key}' is not a valid CIDR network.");
}

static bool IsValidCidrKey(string key) => NetworkAddress.TryParse(key, out NetworkAddress _);

When it happens

Trigger: Calling the Dns64App initializer with a 'networkGroupMap' key that NetworkAddress.TryParse rejects: a hostname, a bare IP without prefix, a malformed CIDR, or an endpoint with a port.

Common situations: Using a single IPv6 client address without '/128'; pasting '2001:db8::1' instead of the subnet '2001:db8::/64'; CIDR typo; DNS64 NAT64 client prefix mistakenly placed in the network map.

Related errors

• Network group map contains an invalid network address: {netw
• Network group map contains an invalid network address: {netw
• DNS64 prefix can have only the following prefixes: 32, 40, 4
• An IPv6 network address is expected for 'excludedIpv6' array
• Local end point group map contains an invalid end point: {lo

AI-assisted analysis of TechnitiumSoftware/DnsServer@d0484b6c1e (2026-08-13). Data as JSON: /api/errors/529016a8ea9360cf. Report an issue: GitHub.