diff --git a/Lib/idlelib/GrepDialog.py b/Lib/idlelib/GrepDialog.py
index 01e0483d4b2..27fcc33c329 100644
--- a/Lib/idlelib/GrepDialog.py
+++ b/Lib/idlelib/GrepDialog.py
@@ -81,7 +81,7 @@ class GrepDialog(SearchDialogBase):
         hits = 0
         for fn in list:
             try:
-                f = open(fn)
+                f = open(fn, errors='replace')
             except IOError as msg:
                 print(msg)
                 continue
diff --git a/Misc/NEWS b/Misc/NEWS
index 3ea0ae30dff..2b457232f2e 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -67,6 +67,9 @@ Core and Builtins
 Library
 -------
 
+- Issue14929: Stop Idle 3.x from closing on Unicode decode errors when grepping.
+  Patch by Roger Serwy.
+
 - Issue12510: Attempting to get invalid tooltip no longer closes Idle.
   Original patch by Roger Serwy.