Merge from 3.x: PR #4369

Fixes #4191

spyder/plugins/tests/test_ipythonconsole.py

@@ -4,6 +4,7 @@
 # Licensed under the terms of the MIT License
 #
 
+import codecs
 import os
 import os.path as osp
 import shutil
@@ -55,6 +56,23 @@ def close_widget():
 #==============================================================================
 # Tests
 #==============================================================================
+def test_read_stderr(ipyconsole, qtbot):
+    """
+    Test the read operation of the stderr file of the kernel
+    """
+
+    shell = ipyconsole.get_current_shellwidget()
+    client = ipyconsole.get_current_client()
+    qtbot.waitUntil(lambda: shell._prompt_html is not None, timeout=SHELL_TIMEOUT)
+
+    # Set contents of the stderr file of the kernel
+    content = 'Test text'
+    stderr_file = client.stderr_file
+    codecs.open(stderr_file, 'w', 'cp437').write(content)
+    # Assert that content is correct
+    assert content == client._read_stderr()
+
+
 @flaky(max_runs=10)
 @pytest.mark.skipif(os.name == 'nt', reason="It times out on Windows")
 def test_run_doctest(ipyconsole, qtbot):

spyder/widgets/ipythonconsole/client.py

@@ -32,9 +32,11 @@
 from spyder.config.gui import get_font, get_shortcut
 from spyder.utils import icon_manager as ima
 from spyder.utils import sourcecode
+from spyder.utils.encoding import get_coding
 from spyder.utils.programs import TEMPDIR
 from spyder.utils.qthelpers import (add_actions, create_action,
                                     create_toolbutton)
+from spyder.py3compat import to_text_string
 from spyder.widgets.browser import WebView
 from spyder.widgets.mixins import SaveHistoryMixin
 from spyder.widgets.ipythonconsole import ShellWidget
@@ -378,7 +380,17 @@ def restart_kernel(self):
     @Slot(str)
     def kernel_restarted_message(self, msg):
         """Show kernel restarted/died messages."""
-        stderr = codecs.open(self.stderr_file, 'r', encoding='utf-8').read()
+        try:
+            stderr = codecs.open(self.stderr_file, 'r',
+                                 encoding='utf-8').read()
+        except UnicodeDecodeError:
+            # This is needed since the stderr file could be encoded
+            # in something different to utf-8.
+            # See issue 4191
+            try:
+                stderr = self._read_stderr()
+            except:
+                stderr = None
 
         if stderr:
             self.show_kernel_error('<tt>%s</tt>' % stderr)
@@ -438,3 +450,10 @@ def _hide_loading_page(self):
 
         document = self.get_control().document()
         document.contentsChange.disconnect(self._hide_loading_page)
+
+    def _read_stderr(self):
+        """Read the stderr file of the kernel."""
+        stderr_text = open(self.stderr_file, 'rb').read()
+        encoding = get_coding(stderr_text)
+        stderr = to_text_string(stderr_text, encoding)
+        return stderr