prepare for RC5: reset all scala versions to 2.11
diff --git a/README.md b/README.md
index 12a060b..09ca2e1 100644
--- a/README.md
+++ b/README.md
@@ -44,7 +44,7 @@
 ```
 <dependency>
     <groupId>org.apache.mahout</groupId>
-    <artifactId>mahout-math-scala_2.12</artifactId>
+    <artifactId>mahout-math-scala_2.11</artifactId>
     <version>${mahout.version}</version>
 </dependency>
 ```
@@ -52,7 +52,7 @@
 ```
 <dependency>
     <groupId>org.apache.mahout</groupId>
-    <artifactId>mahout-spark_2.12</artifactId>
+    <artifactId>mahout-spark_2.11</artifactId>
     <version>${mahout.version}</version>
 </dependency>
 ```
diff --git a/community/community-engines/flink-batch/pom.xml b/community/community-engines/flink-batch/pom.xml
index 3e33d35..cf29e02 100644
--- a/community/community-engines/flink-batch/pom.xml
+++ b/community/community-engines/flink-batch/pom.xml
@@ -22,12 +22,12 @@
 
   <parent>
     <groupId>org.apache.mahout</groupId>
-    <artifactId>mahout-community-engines_2.12</artifactId>
+    <artifactId>mahout-community-engines_2.11</artifactId>
     <version>14.1-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>mahout-flink-batch_2.12</artifactId>
+  <artifactId>mahout-flink-batch_2.11</artifactId>
   <name>-- Mahout Flink Engine (Community)</name>
   <description>
     Mahout Bindings for Apache Flink
@@ -125,7 +125,7 @@
 
       <!-- enable scalatest -->
       <plugin>
-        <groupId>org.scalatest_2.12</groupId>
+        <groupId>org.scalatest_2.11</groupId>
         <artifactId>scalatest-maven-plugin</artifactId>
         <executions>
           <execution>
diff --git a/community/community-engines/h2o/pom.xml b/community/community-engines/h2o/pom.xml
index 666bbb1..608100b 100644
--- a/community/community-engines/h2o/pom.xml
+++ b/community/community-engines/h2o/pom.xml
@@ -22,12 +22,12 @@
 
   <parent>
     <groupId>org.apache.mahout</groupId>
-    <artifactId>mahout-community-engines_2.12</artifactId>
+    <artifactId>mahout-community-engines_2.11</artifactId>
     <version>14.1-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>mahout-h2o_2.12</artifactId>
+  <artifactId>mahout-h2o_2.11</artifactId>
   <name>-- Mahout H2O Engine (Community)</name>
   <description>
     H2O Backend for Mahout DSL
diff --git a/community/community-engines/pom.xml b/community/community-engines/pom.xml
index ebce3da..52f4acb 100644
--- a/community/community-engines/pom.xml
+++ b/community/community-engines/pom.xml
@@ -22,7 +22,7 @@
 
   <parent>
     <groupId>org.apache.mahout</groupId>
-    <artifactId>mahout-community_2.12</artifactId>
+    <artifactId>mahout-community_2.11</artifactId>
     <version>14.1-SNAPSHOT</version>
     <relativePath>../pom.xml</relativePath>
   </parent>
@@ -36,7 +36,7 @@
     </tag>
   </scm>
 
-  <artifactId>mahout-community-engines_2.12</artifactId>
+  <artifactId>mahout-community-engines_2.11</artifactId>
   <name>- Mahout Community Supported Engines</name>
   <description>Not officially maintained Mahout Engines
   </description>
diff --git a/community/spark-cli-drivers/pom.xml b/community/spark-cli-drivers/pom.xml
index a5bb3f4..5a7a058 100644
--- a/community/spark-cli-drivers/pom.xml
+++ b/community/spark-cli-drivers/pom.xml
@@ -27,7 +27,7 @@
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>mahout-spark-cli-drivers_2.12</artifactId>
+  <artifactId>mahout-spark-cli-drivers_2.11</artifactId>
   <name>- Mahout Spark CLI Drivers</name>
   <description>These drivers will allow you to compile a handy Apache Spark App which utilizes Apache Mahout.
   </description>
diff --git a/core/pom.xml b/core/pom.xml
index e92c2be..b2fab2b 100644
--- a/core/pom.xml
+++ b/core/pom.xml
@@ -27,7 +27,7 @@
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>mahout-core_2.12</artifactId>
+  <artifactId>mahout-core_2.11</artifactId>
   <name>Mahout Core</name>
   <description>High performance scientific and technical computing data structures and methods,
     mostly based on CERN's Colt Java API
diff --git a/distribution/pom.xml b/distribution/pom.xml
index 340420a..1826494 100644
--- a/distribution/pom.xml
+++ b/distribution/pom.xml
@@ -26,7 +26,7 @@
         <version>14.1-SNAPSHOT</version>
     </parent>
 
-    <artifactId>apache-mahout-distribution_2.12</artifactId>
+    <artifactId>apache-mahout-distribution_2.11</artifactId>
 
     <name>Mahout Release Package</name>
     <description>Distribution Package</description>
diff --git a/engine/hdfs/pom.xml b/engine/hdfs/pom.xml
index 83b24cc..092416c 100644
--- a/engine/hdfs/pom.xml
+++ b/engine/hdfs/pom.xml
@@ -28,7 +28,7 @@
   </parent>
 
   <!-- modules inherit parent's group id and version. -->
-  <artifactId>mahout-hdfs_2.12</artifactId>
+  <artifactId>mahout-hdfs_2.11</artifactId>
   <name>- Mahout HDFS Support</name>
   <description>Scalable machine learning libraries</description>
 
diff --git a/engine/spark/pom.xml b/engine/spark/pom.xml
index 33a05c2..df573c8 100644
--- a/engine/spark/pom.xml
+++ b/engine/spark/pom.xml
@@ -27,7 +27,7 @@
     <relativePath>../pom.xml</relativePath>
   </parent>
 
-  <artifactId>mahout-spark_2.12</artifactId>
+  <artifactId>mahout-spark_2.11</artifactId>
   <name>- Mahout Spark Engine</name>
   <description>
     Mahout Bindings for Apache Spark
diff --git a/engine/spark/src/main/assembly/dependency-reduced.xml b/engine/spark/src/main/assembly/dependency-reduced.xml
index d30f458..78a03cd 100644
--- a/engine/spark/src/main/assembly/dependency-reduced.xml
+++ b/engine/spark/src/main/assembly/dependency-reduced.xml
@@ -42,8 +42,8 @@
 <!--        <include>com.tdunning:t-digest</include>-->
         <include>org.apache.commons:commons-math3</include>
         <include>it.unimi.dsi:fastutil</include>
-        <include>org.apache.mahout:mahout-native-viennacl_2.12</include>
-        <include>org.apache.mahout:mahout-native-viennacl-omp_2.12</include>
+        <include>org.apache.mahout:mahout-native-viennacl_2.11</include>
+        <include>org.apache.mahout:mahout-native-viennacl-omp_2.11</include>
         <include>org.bytedeco:javacpp</include>
       </includes>
     </dependencySet>
diff --git a/engine/spark/src/main/scala/org/apache/mahout/sparkbindings/package.scala b/engine/spark/src/main/scala/org/apache/mahout/sparkbindings/package.scala
index 4ca2827..b0b5a29 100644
--- a/engine/spark/src/main/scala/org/apache/mahout/sparkbindings/package.scala
+++ b/engine/spark/src/main/scala/org/apache/mahout/sparkbindings/package.scala
@@ -266,7 +266,7 @@
       // j.matches(".*mahout-mr-\\d.*\\.jar") ||
       j.matches(".*spark_\\d.*\\.jar") ||
       // vcl jars: mahout-native-viennacl_2.11.jar,
-      //           mahout-native-viennacl-omp_2.12.jar
+      //           mahout-native-viennacl-omp_2.11.jar
 //      j.matches(".*mahout-native-viennacl_\\d.*\\\\.jar") ||
 //      j.matches(".*mahout-native-viennacl-omp_\\d.*\\.jar")||
         j.matches(".*mahout-native-viennacl*.jar")||
diff --git a/pom.xml b/pom.xml
index 000b7ac..134849e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -109,8 +109,8 @@
     <maven.compiler.target>1.8</maven.compiler.target>
     <mjavadoc.version>2.10.3</mjavadoc.version>
     <slf4j.version>1.7.22</slf4j.version>
-    <scala.version>2.12.8</scala.version>
-    <scala.compat.version>2.12</scala.compat.version>
+    <scala.version>2.11.8</scala.version>
+    <scala.compat.version>2.11</scala.compat.version>
     <source.plugin.version>3.0.1</source.plugin.version>
     <spark.version>2.4.3</spark.version>
     <spark.compat.version>2.4</spark.compat.version>
diff --git a/website/docs/latest/tutorials/misc/mahout-in-zeppelin/index.md b/website/docs/latest/tutorials/misc/mahout-in-zeppelin/index.md
index 4a4d07c..f5b15c0 100644
--- a/website/docs/latest/tutorials/misc/mahout-in-zeppelin/index.md
+++ b/website/docs/latest/tutorials/misc/mahout-in-zeppelin/index.md
@@ -118,19 +118,19 @@
         <th>exclude</th>
     </tr>
     <tr>
-        <td>/path/to/mahout/core_2.12-0.14.jar</td>
+        <td>/path/to/mahout/core_2.11-0.14.jar</td>
         <td></td>
     </tr>
      <tr>
-        <td>path/to/mahout/mahout-hdfs_2.12-0.14.jar</td>
+        <td>path/to/mahout/mahout-hdfs_2.11-0.14.jar</td>
         <td></td>
      </tr>
     <tr>
-        <td>/path/to/mahout/mahout-spark_2.12-0.14.jar</td>
+        <td>/path/to/mahout/mahout-spark_2.11-0.14.jar</td>
         <td></td>
     </tr>  
     <tr>
-        <td>/path/to/mahout/mahout-spark_2.12-0.14.jar-dependeny-reduced.jar</td>
+        <td>/path/to/mahout/mahout-spark_2.11-0.14.jar-dependeny-reduced.jar</td>
         <td></td>
     </tr>
 </table>
@@ -149,15 +149,15 @@
         <td></td>
     </tr>
     <tr>
-        <td>org.apache.mahout:mahout-hdfs-scala_2.12:0.14</td>
+        <td>org.apache.mahout:mahout-hdfs-scala_2.11:0.14</td>
         <td></td>
     </tr>
     <tr>
-        <td>org.apache.mahout:mahout-spark_2.12:0.14</td>
+        <td>org.apache.mahout:mahout-spark_2.11:0.14</td>
         <td></td>
     </tr>
      <tr>
-         <td>org.apache.mahout:mahout-native-viennacl-omp_2.12:0.14</td>
+         <td>org.apache.mahout:mahout-native-viennacl-omp_2.11:0.14</td>
          <td></td>
      </tr> 
 
@@ -175,12 +175,12 @@
         <th>type of native solver</th>
     </tr>
      <tr>
-         <td>org.apache.mahout:mahout-native-viennacl_2.12:0.14</td>
+         <td>org.apache.mahout:mahout-native-viennacl_2.11:0.14</td>
          <td></td>
          <td>ViennaCL GPU Accelerated</td>
      </tr> 
      <tr>
-         <td>org.apache.mahout:mahout-native-viennacl-omp_2.12:0.14</td>
+         <td>org.apache.mahout:mahout-native-viennacl-omp_2.11:0.14</td>
          <td></td>
          <td>ViennaCL-OMP CPU Accelerated (use this if you don't have a good graphics card)</td>
      </tr>