Note that TLS issues with VNC may still affect older versions of libvncclient.
diff --git a/_releases/1.2.0.md b/_releases/1.2.0.md
index 4b1607f..72cb9e4 100644
--- a/_releases/1.2.0.md
+++ b/_releases/1.2.0.md
@@ -310,6 +310,20 @@
resulting in unstable behavior. These callbacks are now correctly specified,
and connections to VNC servers requiring TLS should function correctly.
+Beware that these callbacks are only supported in newer versions of
+libvncclient. If the version of libvncclient installed lacks support for these
+callbacks, a warning will be displayed when building guacamole-server noting
+that TLS may not work correctly:
+
+ checking for rfbClient.LockWriteToTLS... no
+ checking for rfbClient.UnlockWriteToTLS... no
+ configure: WARNING:
+ --------------------------------------------
+ This version of libvncclient lacks support
+ for TLS locking. VNC connections that use
+ TLS may experience instability as documented
+ in GUACAMOLE-414
+
* [GUACAMOLE-414](https://issues.apache.org/jira/browse/GUACAMOLE-414) - Certain VNC servers result in disconnection due to TLS errors
### Rendering of balancing groups
