diff --git a/hgext/convert/subversion.py b/hgext/convert/subversion.py
--- a/hgext/convert/subversion.py
+++ b/hgext/convert/subversion.py
@@ -146,7 +146,7 @@
         # Caller may interrupt the iteration
         pickle.dump(None, fp, protocol)
     except Exception as inst:
-        pickle.dump(str(inst), fp, protocol)
+        pickle.dump(pycompat.bytestr(inst), fp, protocol)
     else:
         pickle.dump(None, fp, protocol)
     fp.flush()
diff --git a/hgext/gpg.py b/hgext/gpg.py
--- a/hgext/gpg.py
+++ b/hgext/gpg.py
@@ -317,7 +317,7 @@
         repo.commit(message, opts['user'], opts['date'], match=msigs,
                     editor=editor)
     except ValueError as inst:
-        raise error.Abort(str(inst))
+        raise error.Abort(pycompat.bytestr(inst))
 
 def node2txt(repo, node, ver):
     """map a manifest into some text"""
diff --git a/hgext/journal.py b/hgext/journal.py
--- a/hgext/journal.py
+++ b/hgext/journal.py
@@ -507,7 +507,7 @@
                     ctx = repo[hash]
                     displayer.show(ctx)
                 except error.RepoLookupError as e:
-                    fm.write('repolookuperror', "%s\n\n", str(e))
+                    fm.write('repolookuperror', "%s\n\n", pycompat.bytestr(e))
             displayer.close()
 
     fm.end()
diff --git a/hgext/largefiles/overrides.py b/hgext/largefiles/overrides.py
--- a/hgext/largefiles/overrides.py
+++ b/hgext/largefiles/overrides.py
@@ -598,7 +598,7 @@
     try:
         result = orig(ui, repo, pats, opts, rename)
     except error.Abort as e:
-        if str(e) != _('no files to copy'):
+        if pycompat.bytestr(e) != _('no files to copy'):
             raise e
         else:
             nonormalfiles = True
@@ -705,7 +705,7 @@
                 lfdirstate.add(destlfile)
         lfdirstate.write()
     except error.Abort as e:
-        if str(e) != _('no files to copy'):
+        if pycompat.bytestr(e) != _('no files to copy'):
             raise e
         else:
             nolfiles = True
diff --git a/hgext/mq.py b/hgext/mq.py
--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -722,7 +722,8 @@
         try:
             os.unlink(undo)
         except OSError as inst:
-            self.ui.warn(_('error removing undo: %s\n') % str(inst))
+            self.ui.warn(_('error removing undo: %s\n') % \
+                         pycompat.bytestr(inst))
 
     def backup(self, repo, files, copy=False):
         # backup local changes in --force case
diff --git a/hgext/narrow/narrowbundle2.py b/hgext/narrow/narrowbundle2.py
--- a/hgext/narrow/narrowbundle2.py
+++ b/hgext/narrow/narrowbundle2.py
@@ -25,6 +25,7 @@
     exchange,
     extensions,
     narrowspec,
+    pycompat,
     repair,
     util,
     wireproto,
@@ -449,7 +450,7 @@
         except OSError as e:
             if e.errno != errno.ENOENT:
                 ui.warn(_('error removing %s: %s\n') %
-                        (undovfs.join(undofile), str(e)))
+                        (undovfs.join(undofile), pycompat.bytestr(e)))
 
     # Remove partial backup only if there were no exceptions
     vfs.unlink(chgrpfile)
diff --git a/hgext/relink.py b/hgext/relink.py
--- a/hgext/relink.py
+++ b/hgext/relink.py
@@ -187,7 +187,7 @@
             relinked += 1
             savedbytes += sz
         except OSError as inst:
-            ui.warn('%s: %s\n' % (tgt, str(inst)))
+            ui.warn('%s: %s\n' % (tgt, pycompat.bytestr(inst)))
 
     ui.progress(_('relinking'), None)