diff --git a/htroot/yacysearch.html b/htroot/yacysearch.html
index c9e17e618..929d53b49 100644
--- a/htroot/yacysearch.html
+++ b/htroot/yacysearch.html
@@ -115,7 +115,7 @@ $(function() {
 	    #(searchvideo)#::<input type="radio" id="video" name="contentdom" value="video" #(check)#::checked="checked"#(/check)# /><label for="video">Video</label>&nbsp;&nbsp;#(/searchvideo)#
 	    #(searchapp)#::<input type="radio" id="app" name="contentdom" value="app" #(check)#::checked="checked"#(/check)# /><label for="app">Applications</label>#(/searchapp)#
         &nbsp;
-        <a href="index.html?searchoptions=1&amp;count=#[count]#&amp;urlmaskfilter=#[urlmaskfilter]#&amp;prefermaskfilter=#[prefermaskfilter]#&amp;cat=#[cat]#&amp;constraint=#[constraint]#&amp;contentdom=#[contentdom]#&amp;former=#[former]#&amp;meanCount=#[meanCount]#">more options</a>
+        <a href="index.html?searchoptions=2&amp;count=#[count]#&amp;urlmaskfilter=#[urlmaskfilter]#&amp;prefermaskfilter=#[prefermaskfilter]#&amp;cat=#[cat]#&amp;constraint=#[constraint]#&amp;contentdom=#[contentdom]#&amp;former=#[former]#&amp;meanCount=#[meanCount]#">more options</a>
     </div>
     #(/searchdomswitches)#
     <input type="hidden" name="former" value="#[former]#" />
@@ -132,6 +132,14 @@ $(function() {
     <input type="hidden" name="meanCount" value="#[meanCount]#" />
   </fieldset>
 </form>
+#(urlmaskerror)#::
+<p><b>Illegal URL mask:</b> <i>#[urlmask]#</i> (not a valid regular expression), mask ignored.</p>
+#(/urlmaskerror)#
+
+#(prefermaskerror)#::
+<p><b>Illegal prefer mask:</b> <i>#[prefermask]#</i> (not a valid regular expression), mask ignored.</b></p>
+#(/prefermaskerror)#
+
 #(didYouMean)#::
 <p><b>Did you mean:</b> #{suggestions}# <a href="#[url]#">#[word]#</a> #[sep]##{/suggestions}#</p>
 #(/didYouMean)#
diff --git a/htroot/yacysearch.java b/htroot/yacysearch.java
index 00bb2d382..0780bc1f2 100644
--- a/htroot/yacysearch.java
+++ b/htroot/yacysearch.java
@@ -33,6 +33,8 @@ import java.util.Iterator;
 import java.util.Map;
 import java.util.SortedSet;
 import java.util.TreeSet;
+import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
 
 import net.yacy.cora.document.RSSMessage;
 import net.yacy.cora.document.UTF8;
@@ -191,11 +193,11 @@ public class yacysearch {
         }
 
         String prefermask = (post == null) ? "" : post.get("prefermaskfilter", "");
-        if (prefermask.length() > 0 && prefermask.indexOf(".*") < 0) {
+        if (!prefermask.isEmpty() && prefermask.indexOf(".*") < 0) {
             prefermask = ".*" + prefermask + ".*";
         }
 
-        Bitfield constraint = (post != null && post.containsKey("constraint") && post.get("constraint", "").length() > 0) ? new Bitfield(4, post.get("constraint", "______")) : null;
+        Bitfield constraint = (post != null && post.containsKey("constraint") && !post.get("constraint", "").isEmpty()) ? new Bitfield(4, post.get("constraint", "______")) : null;
         if (indexof) {
             constraint = new Bitfield(4);
             constraint.set(Condenser.flag_cat_indexof, true);
@@ -475,6 +477,26 @@ public class yacysearch {
         
             // do the search
             final HandleSet queryHashes = Word.words2hashesHandles(query[0]);
+
+            // check filters
+            try {
+                Pattern.compile(urlmask);
+            } catch (final PatternSyntaxException ex) {
+                Log.logWarning("SEARCH", "Illegal URL mask, not a valid regex: " + urlmask);
+                prop.put("urlmaskerror", 1);
+                prop.putHTML("urlmaskerror_urlmask", urlmask);
+                urlmask = ".*";
+            }
+
+            try {
+                Pattern.compile(prefermask);
+            } catch (final PatternSyntaxException ex) {
+                Log.logWarning("SEARCH", "Illegal prefer mask, not a valid regex: " + prefermask);
+                prop.put("prefermaskerror", 1);
+                prop.putHTML("prefermaskerror_prefermask", prefermask);
+                prefermask = "";
+            }
+
             final QueryParams theQuery = new QueryParams(
                     originalquerystring,
                     queryHashes,
diff --git a/source/de/anomic/search/QueryParams.java b/source/de/anomic/search/QueryParams.java
index 0aa337535..47edde209 100644
--- a/source/de/anomic/search/QueryParams.java
+++ b/source/de/anomic/search/QueryParams.java
@@ -34,6 +34,7 @@ import java.util.Map;
 import java.util.SortedSet;
 import java.util.TreeSet;
 import java.util.regex.Pattern;
+import java.util.regex.PatternSyntaxException;
 
 import net.yacy.cora.document.MultiProtocolURI;
 import net.yacy.cora.document.UTF8;
@@ -191,9 +192,17 @@ public final class QueryParams {
         this.contentdom = contentdom;
         this.itemsPerPage = Math.min((specialRights) ? 1000 : 100, itemsPerPage);
         this.offset = Math.min((specialRights) ? 10000 : 1000, offset);
-        this.urlMask = Pattern.compile(urlMask.toLowerCase());
+        try {
+            this.urlMask = Pattern.compile(urlMask.toLowerCase());
+        } catch (final PatternSyntaxException ex) {
+            throw new IllegalArgumentException("Not a valid regular expression: " + urlMask, ex);
+        }
         this.urlMask_isCatchall = this.urlMask.toString().equals(catchall_pattern.toString());
-        this.prefer = Pattern.compile(prefer);
+        try {
+            this.prefer = Pattern.compile(prefer);
+        } catch (final PatternSyntaxException ex) {
+            throw new IllegalArgumentException("Not a valid regular expression: " + prefer, ex);
+        }
         this.prefer_isMatchnothing = this.prefer.toString().equals(matchnothing_pattern.toString());
         assert language != null;
         this.targetlang = language;
@@ -204,7 +213,7 @@ public final class QueryParams {
         this.constraint = constraint;
         this.allofconstraint = allofconstraint;
         this.sitehash = site; assert site == null || site.length() == 6;
-        this.authorhash = authorhash; assert authorhash == null || authorhash.length() > 0;
+        this.authorhash = authorhash; assert authorhash == null || !authorhash.isEmpty();
         this.snippetCacheStrategy = snippetCacheStrategy;
         this.host = host;
         this.remotepeer = null;
@@ -326,7 +335,7 @@ public final class QueryParams {
         final TreeSet<String> exclude = new TreeSet<String>(NaturalOrder.naturalComparator);
         final TreeSet<String> fullquery = new TreeSet<String>(NaturalOrder.naturalComparator);
         
-        if ((querystring != null) && (querystring.length() > 0)) {
+        if ((querystring != null) && (!querystring.isEmpty())) {
         
             // convert Umlaute
             querystring = AbstractScraper.stripAll(querystring.toCharArray()).toLowerCase().trim();
@@ -341,20 +350,20 @@ public final class QueryParams {
             int l;
             // the string is clean now, but we must generate a set out of it
             final String[] queries = querystring.split(" ");
-            for (int i = 0; i < queries.length; i++) {
-                if (queries[i].startsWith("-")) {
-                    exclude.add(queries[i].substring(1));
+            for (String quer : queries) {
+                if (quer.startsWith("-")) {
+                    exclude.add(quer.substring(1));
                 } else {
-                    while ((c = queries[i].indexOf('-')) >= 0) {
-                        s = queries[i].substring(0, c);
+                    while ((c = quer.indexOf('-')) >= 0) {
+                        s = quer.substring(0, c);
                         l = s.length();
                         if (l >= Condenser.wordminsize) {query.add(s);}
                         if (l > 0) {fullquery.add(s);}
-                        queries[i] = queries[i].substring(c + 1);
+                        quer = quer.substring(c + 1);
                     }
-                    l = queries[i].length();
-                    if (l >= Condenser.wordminsize) {query.add(queries[i]);}
-                    if (l > 0) {fullquery.add(queries[i]);}
+                    l = quer.length();
+                    if (l >= Condenser.wordminsize) {query.add(quer);}
+                    if (l > 0) {fullquery.add(quer);}
                 }
             }
         }
@@ -364,7 +373,7 @@ public final class QueryParams {
     public String queryString(final boolean encodeHTML) {
         final String ret;
     	if (encodeHTML){
-            ret =CharacterCoding.unicode2html(this.queryString, true);
+            ret = CharacterCoding.unicode2html(this.queryString, true);
     	} else {
             ret = this.queryString;
         }
@@ -375,7 +384,7 @@ public final class QueryParams {
     	try {
             return URLEncoder.encode(this.queryString, "UTF-8");
         } catch (UnsupportedEncodingException e) {
-            e.printStackTrace();
+            Log.logException(e);
             return this.queryString;
         }
     }
@@ -388,7 +397,7 @@ public final class QueryParams {
         // filter out words that appear in this set
     	// this is applied to the queryHashes
     	final HandleSet blues = Word.words2hashesHandles(blueList);
-    	for (byte[] b: blues) queryHashes.remove(b);
+    	for (final byte[] b: blues) queryHashes.remove(b);
     }