diff --git a/cylc/flow/config.py b/cylc/flow/config.py
index 771b8cb8187..e048f9b1825 100644
--- a/cylc/flow/config.py
+++ b/cylc/flow/config.py
@@ -1764,7 +1764,7 @@ def generate_triggers(self, lexpression, left_nodes, right, seq,
                 )
 
             # Call the xtrigger's validate_config function if it has one.
-            with suppress(AttributeError):
+            with suppress(AttributeError, ImportError):
                 get_func(xtrig.func_name, "validate_config", self.fdir)(
                     xtrig.func_args,
                     xtrig.func_kwargs,