diff --git a/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/hgweb.py b/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/hgweb.py
index e2e7d8e931..7f99a85585 100644
--- a/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/hgweb.py
+++ b/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/hgweb.py
@@ -36,7 +36,11 @@ from mercurial.hgweb import hgweb, wsgicgi
 
 demandimport.enable()
 
-u = uimod.ui()
+try:
+    u = uimod.ui.load()
+except AttributeError:
+    # For installations earlier than Mercurial 4.1
+    u = uimod.ui()
 
 # pass SCM_HTTP_POST_ARGS to enable experimental httppostargs protocol of mercurial
 # SCM_HTTP_POST_ARGS is set by HgCGIServlet
diff --git a/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/scmhooks.py b/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/scmhooks.py
index e9a58d589f..d4999cf2fd 100644
--- a/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/scmhooks.py
+++ b/scm-plugins/scm-hg-plugin/src/main/resources/sonia/scm/python/scmhooks.py
@@ -46,7 +46,7 @@ def printMessages(ui, msgs):
   for line in msgs:
     if line.startswith("_e") or line.startswith("_n"):
       line = line[2:];
-    ui.warn(line);
+    ui.warn('%s\n' % line.rstrip())
 
 def callHookUrl(ui, repo, hooktype, node):
   abort = True
@@ -78,8 +78,10 @@ def callHookUrl(ui, repo, hooktype, node):
       printMessages(ui, msg.splitlines(True))
     else:
       ui.warn( "ERROR: scm-hook failed with an unknown error\n" )
+    ui.traceback()
   except ValueError:
     ui.warn( "scm-hook failed with an exception\n" )
+    ui.traceback()
   return abort
 
 def callback(ui, repo, hooktype, node=None, source=None, pending=None, **kwargs):