Index: xwiki-platform-core/xwiki-core/src/main/java/com/xpn/xwiki/XWiki.java
===================================================================
--- xwiki-platform-core/xwiki-core/src/main/java/com/xpn/xwiki/XWiki.java	(revision 11467)
+++ xwiki-platform-core/xwiki-core/src/main/java/com/xpn/xwiki/XWiki.java	(working copy)
@@ -1583,6 +1583,7 @@
                 }
             }
         } catch (Exception e) {
+            LOG.debug("exception during evaluating skin",e);
         }
 
         try {
@@ -1718,6 +1719,7 @@
                 }
             }
         } catch (Exception e) {
+            LOG.debug("exception during getting skin file, revert to default base skin",e);
         }
 
         // If all else fails, use the default base skin, even if the URLs could be invalid.
@@ -1771,8 +1773,14 @@
                     url = urlf.createSkinURL(filename, skin, context);
                 }
                 return urlf.getURL(url, context);
+            } else {
+                if (LOG.isTraceEnabled()) {
+                  LOG.trace("resource does not existsi for path "+path);
+                }
             }
         } catch (Exception e) {
+            LOG.debug("Exception during search of file "
+                        +filename+" in skin "+skin,e);
         }
 
         return null;
@@ -1791,15 +1799,35 @@
             // Try to get it from URL
             if (context.getRequest() != null) {
                 skin = context.getRequest().getParameter("skin");
+                if (LOG.isDebugEnabled()) {
+                  if (skin!=null && !skin.equals("")) {
+                    LOG.debug("skin " + skin + " is get from request");
+                  }
+                }
             }
-
             if ((skin == null) || (skin.equals(""))) {
                 skin = getUserPreference("skin", context);
+                if (LOG.isDebugEnabled()) {
+                  if (skin!=null && !skin.equals("")) {
+                    LOG.debug("skin " + skin + " is get from user preferences");
+                  }
+                }
             }
-            if (skin.equals("")) {
-                skin = Param("xwiki.defaultskin", getDefaultBaseSkin(context));
+            if (skin == null || skin.equals("")) {
+                skin = Param("xwiki.defaultskin",null);
+                if (skin!=null) {
+                  if (LOG.isDebugEnabled()) {
+                    LOG.debug("skin " + skin + " is get from xwiki configuration");
+                  }
+                }else{
+                  skin = getDefaultBaseSkin(context);
+                  if (LOG.isDebugEnabled()) {
+                    LOG.debug("skin " + skin + " is get as default based skin");
+                  }
+                }
             }
         } catch (Exception e) {
+            LOG.warn("exception during finding skin", e);
             skin = getDefaultBaseSkin(context);
         }
         try {
@@ -1810,6 +1838,7 @@
             }
         } catch (XWikiException e) {
             // if it fails here, let's just ignore it
+            LOG.debug("Exception during getting skin",e);
         }
 
         context.put("skin", skin);
@@ -2004,6 +2033,7 @@
                 }
             }
         } catch (Exception e) {
+            LOG.warn("exception during getting preference "+prefname,e);
         }
 
         return getWebPreference(prefname, context);