diff --git a/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomTool.java b/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomTool.java
index f37b0b6..04636f7 100644
--- a/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomTool.java
+++ b/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomTool.java
@@ -44,6 +44,7 @@
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.CheckForNull;
 
 import org.kohsuke.stapler.DataBoundConstructor;
 
@@ -62,7 +63,7 @@ public class CustomTool extends ToolInstallation implements
     private final String exportedPaths;
     private final LabelSpecifics[] labelSpecifics;
     private static final LabelSpecifics[] EMPTY_LABELS = new LabelSpecifics[0];           
-    private transient String correctedHome;
+    private transient String correctedHome = null;
     private final ToolVersionConfig toolVersion;
     private final String additionalVariables;
     
@@ -101,7 +102,10 @@ public LabelSpecifics[] getLabelSpecifics() {
         return (labelSpecifics!=null) ? labelSpecifics : EMPTY_LABELS;
     }
 
-    /**Check if the tool has additional variables set*/
+    /**
+     * Check if the tool has additional environment variables set.
+     * @return true when the tool injects additional environment variables. 
+     */
     public boolean hasAdditionalVariables() {
         return additionalVariables != null;
     }
@@ -180,6 +184,12 @@ public void setInstallations(CustomTool... installations) {
             save();
         }
 
+        /**
+         * Gets a {@link CustomTool} by its name.
+         * @param name A name of the tool to be retrieved.
+         * @return A {@link CustomTool} or null if it has no found
+         */
+        @CheckForNull
         public CustomTool byName(String name) {
             for (CustomTool tool : getInstallations()) {
                 if (tool.getName().equals(name)) {
diff --git a/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapper.java b/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapper.java
index 4031351..f93d5e9 100644
--- a/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapper.java
+++ b/src/main/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapper.java
@@ -28,7 +28,6 @@
 import hudson.Extension;
 import hudson.Launcher;
 import hudson.Proc;
-import hudson.Util;
 import hudson.matrix.MatrixBuild;
 import hudson.model.BuildListener;
 import hudson.model.AbstractBuild;
@@ -42,10 +41,11 @@
 import hudson.tasks.BuildWrapperDescriptor;
 
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Map;
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 
 import net.sf.json.JSONObject;
 
@@ -68,24 +68,41 @@ public class CustomToolInstallWrapper extends BuildWrapper {
      *
      */
     public static class SelectedTool {
-        private String name;
+        private final String name;
         
         @DataBoundConstructor
         public SelectedTool(String name) {
             this.name = name;
         }
+        
         public String getName() {
             return name;
         }
+
+        @Override
+        public String toString() {
+            return name;
+        }
         
+        @CheckForNull
         public CustomTool toCustomTool() {
             return ((CustomTool.DescriptorImpl)Hudson.getInstance().getDescriptor(CustomTool.class)).byName(name);
         }
+        
+        @Nonnull
+        public CustomTool toCustomToolValidated() throws CustomToolException {
+            CustomTool tool = toCustomTool();
+            if (tool == null) {
+                throw new CustomToolException(
+                    Messages.CustomTool_GetToolByName_ErrorMessage(name));
+            }
+            return tool;
+        }
     }
     
     private SelectedTool[] selectedTools = new SelectedTool[0];
-    private MulticonfigWrapperOptions multiconfigOptions;    
-    private boolean convertHomesToUppercase;
+    private final MulticonfigWrapperOptions multiconfigOptions;    
+    private final boolean convertHomesToUppercase;
     
     @DataBoundConstructor
     public CustomToolInstallWrapper(SelectedTool[] selectedTools, MulticonfigWrapperOptions multiconfigOptions, boolean convertHomesToUppercase) {
@@ -93,7 +110,7 @@ public CustomToolInstallWrapper(SelectedTool[] selectedTools, MulticonfigWrapper
         this.multiconfigOptions = (multiconfigOptions != null) ? multiconfigOptions : MulticonfigWrapperOptions.DEFAULT;
         this.convertHomesToUppercase = convertHomesToUppercase;
     }
-
+    
     public boolean isConvertHomesToUppercase() {
         return convertHomesToUppercase;
     }   
@@ -104,13 +121,15 @@ public Environment setUp(AbstractBuild build, Launcher launcher,
         
         final EnvVars buildEnv = build.getEnvironment(listener);
         final Node node = build.getBuiltOn();
-        
-        return new Environment(){            
+         
+        return new Environment() {            
             @Override
-            public void buildEnvVars(Map<String, String> env) {          
+            public void buildEnvVars(Map<String, String> env) {    
+                
                 // TODO: Inject Home dirs as well
-                for (CustomTool tool : customTools()) {
-                    if (tool.hasVersions()) {
+                for (SelectedTool selectedTool : selectedTools) {
+                    CustomTool tool = selectedTool.toCustomTool();
+                    if (tool != null && tool.hasVersions()) {
                         ToolVersion version = ToolVersion.getEffectiveToolVersion(tool, buildEnv, node);   
                         if (version != null && !env.containsKey(version.getVariableName())) {
                             env.put(version.getVariableName(), version.getDefaultVersion());
@@ -125,22 +144,16 @@ public SelectedTool[] getSelectedTools() {
         return selectedTools.clone();
     }
     
-    private List<CustomTool> customTools() {
-        List<CustomTool> tools = new ArrayList<CustomTool>();
-        for (SelectedTool selected : selectedTools) {
-            tools.add(selected.toCustomTool());
-        }
-        return tools;
-    }
-       
     /**
      * The heart of the beast. Installs selected tools and exports their paths to the 
      * PATH and their HOMEs as environment variables.
+     * @return A decorated launcher
      */
     @Override
     public Launcher decorateLauncher(AbstractBuild build, final Launcher launcher,
             BuildListener listener) throws IOException, InterruptedException,
-            RunnerAbortedException { 
+            RunnerAbortedException {
+        
         EnvVars buildEnv = build.getEnvironment(listener); 
         final EnvVars homes = new EnvVars();
         final EnvVars versions = new EnvVars();
@@ -149,8 +162,8 @@ public Launcher decorateLauncher(AbstractBuild build, final Launcher launcher,
         final List<EnvVariablesInjector> additionalVarInjectors = new LinkedList<EnvVariablesInjector>();
         
         // Handle multi-configuration build
-        if (MatrixBuild.class.isAssignableFrom(build.getClass())) {  
-            CustomToolsLogger.LogMessage(listener, "Skipping installation of tools at the master job");
+        if (build instanceof MatrixBuild) {  
+            CustomToolsLogger.logMessage(listener, "Skipping installation of tools at the master job");
             if (multiconfigOptions.isSkipMasterInstallation()) {
                 return launcher;
             }
@@ -158,11 +171,12 @@ public Launcher decorateLauncher(AbstractBuild build, final Launcher launcher,
         
         // Each tool can export zero or many directories to the PATH
         Node node =  Computer.currentComputer().getNode();
-        for (CustomTool tool : customTools()) {
-            CustomToolsLogger.LogMessage(listener, tool.getName(), "Starting installation");
+        for (SelectedTool selectedToolName : selectedTools) {
+            CustomTool tool = selectedToolName.toCustomToolValidated();            
+            CustomToolsLogger.logMessage(listener, tool.getName(), "Starting installation");
             
             // Check versioning
-            CheckVersions(tool, listener, buildEnv, node, versions);
+            checkVersions(tool, listener, buildEnv, node, versions);
             
             // This installs the tool if necessary
             CustomTool installed = tool
@@ -191,16 +205,16 @@ public Launcher decorateLauncher(AbstractBuild build, final Launcher launcher,
                 if (!spec.appliesTo(node)) {
                     continue;
                 }
-                CustomToolsLogger.LogMessage(listener, installed.getName(), "Label specifics from '"+spec.getLabel()+"' will be applied");
+                CustomToolsLogger.logMessage(listener, installed.getName(), "Label specifics from '"+spec.getLabel()+"' will be applied");
                                
                 if (spec.hasAdditionalVars()) {
                     additionalVarInjectors.add(EnvVariablesInjector.Create(spec.getAdditionalVars()));
                 }
             }
             
-            CustomToolsLogger.LogMessage(listener, installed.getName(), "Tool is installed at "+ installed.getHome());
+            CustomToolsLogger.logMessage(listener, installed.getName(), "Tool is installed at "+ installed.getHome());
             String homeDirVarName = (convertHomesToUppercase ? installed.getName().toUpperCase() : installed.getName()) +"_HOME";
-            CustomToolsLogger.LogMessage(listener, installed.getName(), "Setting "+ homeDirVarName+"="+installed.getHome());
+            CustomToolsLogger.logMessage(listener, installed.getName(), "Setting "+ homeDirVarName+"="+installed.getHome());
             homes.put(homeDirVarName, installed.getHome());
         }
 
@@ -248,7 +262,15 @@ private EnvVars toEnvVars(String[] envs) {
     }
     
     /**
-     * Check versions and modify build environment if required.
+     * @deprecated The method is deprecated. It will be removed in future versions.
+     */
+    public void CheckVersions (CustomTool tool, BuildListener listener, EnvVars buildEnv, Node node, EnvVars target) 
+            throws CustomToolException  {
+        checkVersions(tool, listener, buildEnv, node, target);
+    }
+    
+    /**
+     * Checks versions and modify build environment if required.
      * @param tool Custom Tool
      * @param listener Build Listener
      * @param buildEnv Build Environment (can be modified)
@@ -257,16 +279,16 @@ private EnvVars toEnvVars(String[] envs) {
      * @throws CustomToolException 
      * @since 0.4
      */
-    public void CheckVersions (CustomTool tool, BuildListener listener, EnvVars buildEnv, Node node, EnvVars target) throws CustomToolException {
+    public void checkVersions (CustomTool tool, BuildListener listener, EnvVars buildEnv, Node node, EnvVars target) throws CustomToolException {
         // Check version
         if (tool.hasVersions()) {
             ToolVersion version = ToolVersion.getEffectiveToolVersion(tool, buildEnv, node);   
             if (version == null) {
-                CustomToolsLogger.LogMessage(listener, tool.getName(), "Error: No version has been specified, no default version. Failing the build...");
+                CustomToolsLogger.logMessage(listener, tool.getName(), "Error: No version has been specified, no default version. Failing the build...");
                 throw new CustomToolException("Version has not been specified for the "+tool.getName());
             }
             
-            CustomToolsLogger.LogMessage(listener, tool.getName(), "Version "+version.getActualVersion()+" has been specified by "+version.getVersionSource());
+            CustomToolsLogger.logMessage(listener, tool.getName(), "Version "+version.getActualVersion()+" has been specified by "+version.getVersionSource());
             
             // Override default versions
             if (version.getVersionSource().equals(ToolVersion.DEFAULTS_SOURCE)) {            
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/CustomToolsLogger.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/CustomToolsLogger.java
index 2ccac67..e382c1e 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/CustomToolsLogger.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/CustomToolsLogger.java
@@ -18,18 +18,34 @@
 import hudson.model.BuildListener;
 
 /**
- *
+ * Provides logging routines for the plugin.
  * @author Oleg Nenashev <nenashev@synopsys.com>, Synopsys Inc.
  * @since 0.3
  */
 public class CustomToolsLogger {
     public static final String LOG_PREFIX = "[CustomTools] - ";
     
+    /**
+     * @deprecated Use {@link #logMessage(hudson.model.BuildListener, java.lang.String)}
+     * instead.
+     */
     public static void LogMessage(BuildListener listener, String message) {
-        listener.getLogger().println(CustomToolsLogger.LOG_PREFIX+message);
+        logMessage(listener, message);
     }
     
+    /**
+     * @deprecated Use {@link #logMessage(hudson.model.BuildListener, java.lang.String, java.lang.String)}
+     * instead.
+     */
     public static void LogMessage(BuildListener listener, String toolName, String message) {
+        logMessage(listener, toolName, message);
+    }
+    
+    public static void logMessage(BuildListener listener, String message) {
+        listener.getLogger().println(CustomToolsLogger.LOG_PREFIX+message);
+    }
+    
+    public static void logMessage(BuildListener listener, String toolName, String message) {
         listener.getLogger().println(CustomToolsLogger.LOG_PREFIX+toolName+": "+message);
     }
 }
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/EnvVariablesInjector.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/EnvVariablesInjector.java
index d5608ea..7fed038 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/EnvVariablesInjector.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/EnvVariablesInjector.java
@@ -33,7 +33,21 @@ public class EnvVariablesInjector extends TreeMap<String, EnvVariablesInjector.E
 {    
     private EnvVariablesInjector(){}
      
+    /**
+     * @deprecated Use {@link #create(java.lang.String)} instead.
+     * This method will be removed in future versions.
+     */
     public static EnvVariablesInjector Create(String props) throws IOException {
+        return create(props);
+    }
+    
+    /**
+     * Creates a new injector for the specified properties.
+     * @param props Properties in Java Properties format
+     * @return A new injector
+     * @throws IOException Cannot load properties from the string
+     */
+    public static EnvVariablesInjector create(String props) throws IOException {
         Properties prop = new Properties();
         StringReader rdr = new StringReader(props);       
         prop.load(rdr);
@@ -48,12 +62,20 @@ public static EnvVariablesInjector Create(String props) throws IOException {
         return vars;
     }
     
+    /**
+     * @deprecated Use {@link #injectVariables(hudson.EnvVars)} instead.
+     * This method will be removed in future versions.
+     */
+    public void Inject(EnvVars target) throws IOException {
+        injectVariables(target);
+    }
+    
     /**
      * Inject variables into EnvVars
      * @param target Target variables
      * @throws IOException Exception during modification of EnvVars
      */
-    public void Inject(EnvVars target) throws IOException {
+    public void injectVariables(EnvVars target) throws IOException {
         for (Entry<String, EnvVariablesInjector.Entity> entry: entrySet()) {
             entry.getValue().Inject(target);
         }
@@ -94,17 +116,25 @@ public Entity(String envName, String envValue, String listDelimiter,
         {
             this.envName = envName;
             this.envValue = envValue;
-            this.listDelimiter = listDelimiter;
-            this.isList = isList;
-            this.isOverrides = isOverrides;         
+         //   this.listDelimiter = listDelimiter;
+         //   this.isList = isList;
+         //   this.isOverrides = isOverrides;         
         }
         
+       /**
+        * @deprecated Use {@link #injectVariables(hudson.EnvVars)} instead.
+        * This method will be removed in future versions.
+        */
+       public void Inject(EnvVars target) throws IOException {
+           injectVariables(target);
+       } 
+        
        /**
         * Inject variables into EnvVars
         * @param target Target environment
         * @throws IOException Exception during modification of EnvVars
         */
-        public void Inject(EnvVars target) throws IOException {
+        public void injectVariables(EnvVars target) throws IOException {
             //TODO: check overrides
             //TODO: check lists 
             //TODO: substitute, check, etc.
@@ -115,7 +145,5 @@ public void Inject(EnvVars target) throws IOException {
             
             target.put(envName, newEnvValue);
         }
-    }
-    
-    
+    }  
 }
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/LabelSpecifics.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/LabelSpecifics.java
index b18790c..81b12ae 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/LabelSpecifics.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/LabelSpecifics.java
@@ -19,7 +19,6 @@
 import hudson.Extension;
 import hudson.Util;
 import hudson.model.AbstractDescribableImpl;
-import hudson.model.Describable;
 import hudson.model.Descriptor;
 import hudson.model.Label;
 import hudson.model.Node;
@@ -33,9 +32,10 @@
  * @since 0.3
  */
 public class LabelSpecifics extends AbstractDescribableImpl<LabelSpecifics> implements Serializable {
-    private String label;
-    private String additionalVars;
-    private String exportedPaths;
+    
+    private final String label;
+    private final String additionalVars;
+    private final String exportedPaths;
     
     @DataBoundConstructor
     public LabelSpecifics(String label, String additionalVars, String exportedPaths) {
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/PathsList.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/PathsList.java
index 937345f..027ce24 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/PathsList.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/PathsList.java
@@ -38,6 +38,7 @@ public class PathsList implements Serializable {
     /**
      * Constructor. Sets system's default separator and pathSeparator
      * @param paths List of paths to be returned
+     * @param homeDir Home directory of the tool
      */
     public PathsList(Collection<String> paths, String homeDir) {
         this(paths, File.pathSeparator, File.separator, homeDir);
@@ -87,7 +88,7 @@ public boolean add(PathsList pathsList) {
     }
     
     /**
-     * Gets the list of installed tools
+     * Gets the list of installed tools.
      * @return A list with valid delimiters or null if paths is empty
      */
     public String toListString() {
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionConfig.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionConfig.java
index d8c3687..b58b1da 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionConfig.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionConfig.java
@@ -32,7 +32,7 @@ public class ToolVersionConfig extends AbstractDescribableImpl<ToolVersionConfig
     implements Serializable 
 {
     public static final ToolVersionConfig DEFAULT = null;
-    ExtendedChoiceParameterDefinition versionsListSource;
+    private final ExtendedChoiceParameterDefinition versionsListSource;
 
     @DataBoundConstructor
     public ToolVersionConfig(ExtendedChoiceParameterDefinition versionsListSource) {
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionHelper.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionHelper.java
index 69ec33f..2c77dc7 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionHelper.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionHelper.java
@@ -43,8 +43,11 @@ public static String getDefaultVersionVariableName(String toolName) {
     
     public static ExtendedChoiceParameterDefinition getVersionDescr(String toolName) {
         CustomTool.DescriptorImpl tools = ToolInstallation.all().get(CustomTool.DescriptorImpl.class);
-        CustomTool tool = tools.byName(toolName);      
-        return tool.hasVersions() ? tool.getToolVersion().getVersionsListSource() : getDefaultVersionDescr(toolName);
+        CustomTool tool = tools.byName(toolName);  
+        
+        return tool != null && tool.hasVersions() 
+                ? tool.getToolVersion().getVersionsListSource() 
+                : getDefaultVersionDescr(toolName);
     }
     
     /**
diff --git a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionParameterDefinition.java b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionParameterDefinition.java
index a9031fd..ff3e6a9 100644
--- a/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionParameterDefinition.java
+++ b/src/main/java/com/synopsys/arc/jenkinsci/plugins/customtools/versions/ToolVersionParameterDefinition.java
@@ -16,6 +16,7 @@
 package com.synopsys.arc.jenkinsci.plugins.customtools.versions;
 
 import com.cloudbees.jenkins.plugins.customtools.CustomTool;
+import com.cwctravel.hudson.plugins.extended_choice_parameter.ExtendedChoiceParameterDefinition;
 import com.cwctravel.hudson.plugins.extended_choice_parameter.ExtendedChoiceParameterValue;
 import com.synopsys.arc.jenkinsci.plugins.customtools.Messages;
 import hudson.Extension;
@@ -23,6 +24,7 @@
 import hudson.model.ParameterDefinition.ParameterDescriptor;
 import hudson.model.StringParameterValue;
 import hudson.tools.ToolInstallation;
+import javax.annotation.CheckForNull;
 import net.sf.json.JSONObject;
 import org.kohsuke.stapler.DataBoundConstructor;
 import org.kohsuke.stapler.StaplerRequest;
@@ -33,7 +35,8 @@
  * @since 0.4
  */
 public class ToolVersionParameterDefinition extends ParameterDefinition {
-    private String toolName;
+    
+    private final String toolName;
     
     @DataBoundConstructor
     public ToolVersionParameterDefinition(String toolName) {
@@ -46,24 +49,50 @@ public String getToolName() {
         return toolName;
     }
     
+    /**
+     * Gets a {@link CustomTool} linked with this Parameter definition.
+     * @return A custom tool or null if it has not been found
+     */
+    @CheckForNull
     public final CustomTool getTool() {
         CustomTool.DescriptorImpl tool = ToolInstallation.all().get(CustomTool.DescriptorImpl.class);
         return tool.byName(toolName);
     }
     
+    /**
+     * Gets a Tool Version configuration for the parameter definition.
+     * @return A tool version configuration or null if the tool cannot be found.
+     */
+    @CheckForNull
     public final ToolVersionConfig getVersionConfig() {
-        return getTool().getToolVersion();
+        CustomTool tool = getTool();
+        return tool != null ? tool.getToolVersion() : null;
+    }
+    
+    private ExtendedChoiceParameterDefinition getVersionsListSource() {
+       ToolVersionConfig versionConfig = getVersionConfig();
+        if (versionConfig == null) {
+            throw new IllegalStateException(
+                    Messages.Versions_ToolVersionParameterDefinition_GetVersionConfigError(toolName));
+        } 
+        
+        return versionConfig.getVersionsListSource(); 
     }
     
     @Override
-    public StringParameterValue createValue(StaplerRequest req, JSONObject jo) {
-        ExtendedChoiceParameterValue paramVal = (ExtendedChoiceParameterValue)getVersionConfig().getVersionsListSource().createValue(req, jo);
+    public StringParameterValue createValue(StaplerRequest req, JSONObject jo)
+            throws IllegalStateException
+    {
+        ExtendedChoiceParameterValue paramVal = (ExtendedChoiceParameterValue) 
+                getVersionsListSource().createValue(req, jo);
         return new StringParameterValue(paramVal.getName(), paramVal.value);
     }
 
     @Override
     public StringParameterValue createValue(StaplerRequest req) {       
-        ExtendedChoiceParameterValue paramVal = (ExtendedChoiceParameterValue)getVersionConfig().getVersionsListSource().createValue(req);
+        
+        ExtendedChoiceParameterValue paramVal = (ExtendedChoiceParameterValue) 
+                getVersionsListSource().createValue(req);
         return new StringParameterValue(paramVal.getName(), paramVal.value);
     }
     
diff --git a/src/main/resources/com/cloudbees/jenkins/plugins/customtools/Messages.properties b/src/main/resources/com/cloudbees/jenkins/plugins/customtools/Messages.properties
index af4eb29..843f4c2 100644
--- a/src/main/resources/com/cloudbees/jenkins/plugins/customtools/Messages.properties
+++ b/src/main/resources/com/cloudbees/jenkins/plugins/customtools/Messages.properties
@@ -1,2 +1,5 @@
 Descriptor.DisplayName=Install custom tools
-CustomTool.DescriptorImpl.DisplayName=Custom tool
\ No newline at end of file
+CustomTool.DescriptorImpl.DisplayName=Custom tool
+CustomTool.GetToolByName.ErrorMessage=  \
+    Cannot find the {0} tool. Probably, it has been deleted from the \
+    global configuration.
\ No newline at end of file
diff --git a/src/main/resources/com/synopsys/arc/jenkinsci/plugins/customtools/Messages.properties b/src/main/resources/com/synopsys/arc/jenkinsci/plugins/customtools/Messages.properties
index 4e01b3c..f339720 100644
--- a/src/main/resources/com/synopsys/arc/jenkinsci/plugins/customtools/Messages.properties
+++ b/src/main/resources/com/synopsys/arc/jenkinsci/plugins/customtools/Messages.properties
@@ -1,3 +1,7 @@
 LabelSpecifics.DisplayName=Label specifics
 Versions.ToolVersionConfig.DisplayName=Tool version
-Versions.ToolVersionParameterDefinition.DisplayName=Tool version
\ No newline at end of file
+Versions.ToolVersionParameterDefinition.DisplayName=Tool version
+Versions.ToolVersionParameterDefinition.GetVersionConfigError=  \
+    Cannot retrieve the version configuration for the tool {0}. Probably, it has been deleted
+Versions.ToolVersionDescription.NoToolError=ERROR: Cannot find the custom tool. \
+    Probably, it has been deleted
\ No newline at end of file
diff --git a/src/test/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapperTest.java b/src/test/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapperTest.java
index c8e57fe..9ea8979 100644
--- a/src/test/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapperTest.java
+++ b/src/test/java/com/cloudbees/jenkins/plugins/customtools/CustomToolInstallWrapperTest.java
@@ -21,6 +21,7 @@
 import com.synopsys.arc.jenkinsci.plugins.customtools.multiconfig.MulticonfigWrapperOptions;
 import hudson.model.FreeStyleBuild;
 import hudson.model.FreeStyleProject;
+import hudson.model.Result;
 import hudson.tasks.BuildWrapper;
 import hudson.tasks.Builder;
 import hudson.tasks.Shell;
@@ -28,6 +29,7 @@
 import java.util.ArrayList;
 import java.util.List;
 import java.util.concurrent.Future;
+import org.jvnet.hudson.test.Bug;
 import org.jvnet.hudson.test.HudsonTestCase;
 
 /**
@@ -36,6 +38,9 @@
  * @author Oleg Nenashev <nenashev@synopsys.com>, Synopsys Inc.
  */
 public class CustomToolInstallWrapperTest extends HudsonTestCase {
+    
+    private static final String NON_EXISTENT_TOOL = "non-existent";
+        
     /**
      * Inserts {@link CustomToolInstallWrapper} after {@link StubWrapper}.
      * @throws Exception 
@@ -73,7 +78,7 @@ public void testNestedLauncherCalls() throws Exception {
         nestedWrapperTestImpl(wrappers, false);
     }
     
-    //@Bug(20560)
+    @Bug(20560)
     public void testEmptyToolsList() throws Exception {
         List<BuildWrapper> wrappers = new ArrayList<BuildWrapper>(0); 
         wrappers.add(new CommandCallerInstaller());
@@ -81,6 +86,24 @@ public void testEmptyToolsList() throws Exception {
         nestedWrapperTestImpl(wrappers, false);
     }
     
+    @Bug(0)
+    public void testDeletedTool() throws Exception {
+        FreeStyleProject project = createFreeStyleProject();
+        
+        CustomToolInstallWrapper.SelectedTool[] tools = 
+                new CustomToolInstallWrapper.SelectedTool[] { 
+                    new CustomToolInstallWrapper.SelectedTool(NON_EXISTENT_TOOL)
+                };
+        
+        project.getBuildWrappersList().add(
+                new CustomToolInstallWrapper(tools, MulticonfigWrapperOptions.DEFAULT, false));
+        
+        Future<FreeStyleBuild> build = project.scheduleBuild2(0);
+        assertBuildStatus(Result.FAILURE, build.get());
+        assertLogContains( 
+                Messages.CustomTool_GetToolByName_ErrorMessage(NON_EXISTENT_TOOL), build.get());
+    }
+    
     /**
      * Implements tests for nested wrappers.
      * The test checks that environment variables have been set correctly.
diff --git a/src/test/java/com/synopsys/arc/jenkins/plugins/customtools/util/StubWrapper.java b/src/test/java/com/synopsys/arc/jenkins/plugins/customtools/util/StubWrapper.java
index 8b7ca8b..0c0523d 100644
--- a/src/test/java/com/synopsys/arc/jenkins/plugins/customtools/util/StubWrapper.java
+++ b/src/test/java/com/synopsys/arc/jenkins/plugins/customtools/util/StubWrapper.java
@@ -28,7 +28,6 @@
 import hudson.tasks.BuildWrapperDescriptor;
 import java.io.IOException;
 import java.util.Map;
-import java.util.TreeMap;
 
 /**
  * A stub wrapper, which injects a test variable into the build environment.
@@ -45,7 +44,6 @@ public class StubWrapper extends BuildWrapper {
     @Override
     public Launcher decorateLauncher(AbstractBuild build, Launcher launcher, BuildListener listener)
             throws IOException, InterruptedException, Run.RunnerAbortedException {
-        final Map<String, String> envs = new TreeMap<String, String>();
       
         return new Launcher.LocalLauncher(listener) {
             @Override