1 files changed, 6 insertions, 0 deletions
diff --git a/develop/print.html b/develop/print.html
index e8325a4b80..b453892ce0 100644
--- a/develop/print.html
+++ b/develop/print.html
@@ -8052,6 +8052,12 @@ servers are using the same module, with the same configuration.</p>
 event with new data by returning the new event's data as a dictionary. In order to do
 that, it is recommended the module calls <code>event.get_dict()</code> to get the current event as a
 dictionary, and modify the returned dictionary accordingly.</p>
+<p>If <code>check_event_allowed</code> raises an exception, the module is assumed to have failed.
+The event will not be accepted but is not treated as explicitly rejected, either.
+An HTTP request causing the module check will likely result in a 500 Internal
+Server Error.</p>
+<p>When the boolean returned by the module is <code>False</code>, the event is rejected.
+(Module developers should not use exceptions for rejection.)</p>
 <p>Note that replacing the event only works for events sent by local users, not for events
 received over federation.</p>
 <p>If multiple modules implement this callback, they will be considered in order. If a