--- a/Sphinx/source/plugins/python.rst	Wed Jan 06 18:29:43 2021 +0100
+++ b/Sphinx/source/plugins/python.rst	Thu Jan 07 09:03:34 2021 +0100
@@ -277,6 +277,19 @@
     orthanc.RegisterOnChangeCallback(OnChange)
 
 
+
+.. warning::
+   Your callback function will be called synchronously with
+   the core of Orthanc. This implies that deadlocks might emerge if
+   you call other core primitives of Orthanc in your callback (such
+   deadlocks are particular visible in the presence of other plugins
+   or Lua scripts). It is thus strongly advised to avoid any call to
+   the REST API of Orthanc in the callback. If you have to call other
+   primitives of Orthanc, you should make these calls in a separate
+   thread, passing the pending events to be processed through a
+   message queue.
+
+
 Accessing the content of a new instance
 .......................................
 
@@ -306,6 +319,18 @@
   orthanc.RegisterOnStoredInstanceCallback(OnStoredInstance)
 
 
+.. warning::
+   Your callback function will be called synchronously with
+   the core of Orthanc. This implies that deadlocks might emerge if
+   you call other core primitives of Orthanc in your callback (such
+   deadlocks are particular visible in the presence of other plugins
+   or Lua scripts). It is thus strongly advised to avoid any call to
+   the REST API of Orthanc in the callback. If you have to call other
+   primitives of Orthanc, you should make these calls in a separate
+   thread, passing the pending events to be processed through a
+   message queue.
+  
+
 Calling pydicom
 ...............