2 files changed, 10 insertions, 6 deletions
diff --git a/Lib/test/libregrtest/main.py b/Lib/test/libregrtest/main.py
index 713cbedb299..0d9c059a938 100644
--- a/Lib/test/libregrtest/main.py
+++ b/Lib/test/libregrtest/main.py
@@ -543,8 +543,6 @@ class Regrtest:
         self.first_runtests = runtests
         self.logger.set_tests(runtests)
 
-        setup_process()
-
         if (runtests.hunt_refleak is not None) and (not self.num_workers):
             # gh-109739: WindowsLoadTracker thread interferes with refleak check
             use_load_tracker = False
@@ -721,10 +719,7 @@ class Regrtest:
         self._execute_python(cmd, environ)
 
     def _init(self):
-        # Set sys.stdout encoder error handler to backslashreplace,
-        # similar to sys.stderr error handler, to avoid UnicodeEncodeError
-        # when printing a traceback or any other non-encodable character.
-        sys.stdout.reconfigure(errors="backslashreplace")
+        setup_process()
 
         if self.junit_filename and not os.path.isabs(self.junit_filename):
             self.junit_filename = os.path.abspath(self.junit_filename)
diff --git a/Lib/test/libregrtest/setup.py b/Lib/test/libregrtest/setup.py
index c3d1f60a400..9bfc414cd61 100644
--- a/Lib/test/libregrtest/setup.py
+++ b/Lib/test/libregrtest/setup.py
@@ -1,5 +1,6 @@
 import faulthandler
 import gc
+import io
 import os
 import random
 import signal
@@ -52,6 +53,14 @@ def setup_process() -> None:
 
     support.record_original_stdout(sys.stdout)
 
+    # Set sys.stdout encoder error handler to backslashreplace,
+    # similar to sys.stderr error handler, to avoid UnicodeEncodeError
+    # when printing a traceback or any other non-encodable character.
+    #
+    # Use an assertion to fix mypy error.
+    assert isinstance(sys.stdout, io.TextIOWrapper)
+    sys.stdout.reconfigure(errors="backslashreplace")
+
     # Some times __path__ and __file__ are not absolute (e.g. while running from
     # Lib/) and, if we change the CWD to run the tests in a temporary dir, some
     # imports might fail.  This affects only the modules imported before os.chdir().