TechnitiumSoftware/DnsServer · error · DhcpServerException

Scope with name '{oldName}' does not exists.

Error message

Scope with name '{oldName}' does not exists.

What it means

RenameScope could not find a scope under oldName in the scopes dictionary, so nothing to rename.

Source

Thrown at DnsServerCore/Dhcp/DhcpServer.cs:1446

        {
            await LoadScopeAsync(scope, false);
            SaveScopeFile(scope);
        }

        public Scope GetScope(string name)
        {
            if (_scopes.TryGetValue(name, out Scope scope))
                return scope;

            return null;
        }

        public void RenameScope(string oldName, string newName)
        {
            Scope.ValidateScopeName(newName);

            if (!_scopes.TryGetValue(oldName, out Scope scope))
                throw new DhcpServerException("Scope with name '" + oldName + "' does not exists.");

            if (!_scopes.TryAdd(newName, scope))
                throw new DhcpServerException("Scope with name '" + newName + "' already exists.");

            scope.Name = newName;
            _scopes.TryRemove(oldName, out _);

            SaveScopeFile(scope);
            DeleteScopeFile(oldName);
        }

        public void DeleteScope(string name)
        {
            if (_scopes.TryGetValue(name, out Scope scope))
            {
                UnloadScope(scope, true);
                DeleteScopeFile(scope.Name);
            }

View on GitHub (pinned to d0484b6c1e)

Solutions

1. Verify the scope exists with GetScope(oldName) before renaming.
2. Use the exact stored Name (mind casing).
3. Refresh the scope list in the caller before issuing the rename.

Example fix

// before
_dhcpServer.RenameScope('Lan', 'lan2'); // stored name is 'lan'
// after
var s = _dhcpServer.GetScope('lan');
if (s != null) _dhcpServer.RenameScope(s.Name, 'lan2');

if (_dhcpServer.GetScope(oldName) == null)
    throw new InvalidOperationException($"Scope '{oldName}' not found");

static bool ScopeExists(Func<string, Scope> getScope, string name) => getScope(name) != null;

try { _dhcpServer.RenameScope(oldName, newName); }
catch (DhcpServerException ex) when (ex.Message.Contains("does not exists"))
{ /* refresh scope list, use exact Name */ }

When it happens

Trigger: Calling RenameScope(oldName, newName) when `_scopes.TryGetValue(oldName, out _)` is false.

Common situations: Stale UI referencing a scope deleted meanwhile. Typo in oldName. Case-sensitivity mismatch (names are treated by dictionary key semantics).

Related errors

• Scope with overlapping range already exists: {existingScope.
• Scope with same name already exists.
• Scope with name '{newName}' already exists.
• The scope name contains an invalid character: {invalidChar}
• The address must be an IPv4 address: {startingAddress}

AI-assisted analysis of TechnitiumSoftware/DnsServer@d0484b6c1e (2026-08-13). Data as JSON: /api/errors/619ae281e72e7dd0. Report an issue: GitHub.