fix exception during DTLS server handshake when the client has no extensions

1 files changed, 1 insertions, 1 deletions

diff --git a/crypto/src/tls/AbstractTlsServer.cs b/crypto/src/tls/AbstractTlsServer.cs

index 9f107d905..352002fbf 100644
--- a/crypto/src/tls/AbstractTlsServer.cs
+++ b/crypto/src/tls/AbstractTlsServer.cs
@@ -604,7 +604,7 @@ namespace Org.BouncyCastle.Tls
                  * RFC 9146 3. When a DTLS session is resumed or renegotiated, the "connection_id" extension is
                  * negotiated afresh.
                  */
-                if (m_clientExtensions.ContainsKey(ExtensionType.connection_id))
+                if (m_clientExtensions != null && m_clientExtensions.ContainsKey(ExtensionType.connection_id))
                 {
                     var serverConnectionID = GetNewConnectionID();
                     if (serverConnectionID != null)