diff --git a/sample-1-2/pom.xml b/sample-1-2/pom.xml
index 0a9909b..c6e1af3 100644
--- a/sample-1-2/pom.xml
+++ b/sample-1-2/pom.xml
@@ -11,7 +11,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.1.2.RELEASE</version>
+        <version>2.3.1.RELEASE</version>
         <relativePath />
     </parent>
 
diff --git a/sample-2-1/pom.xml b/sample-2-1/pom.xml
index f2c5587..2f5a83f 100644
--- a/sample-2-1/pom.xml
+++ b/sample-2-1/pom.xml
@@ -11,7 +11,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.1.2.RELEASE</version>
+        <version>2.3.1.RELEASE</version>
         <relativePath/>
     </parent>
 
diff --git a/sample-2-2/sample-2-2-jdbc-spring/pom.xml b/sample-2-2/sample-2-2-jdbc-spring/pom.xml
index a6db8ac..57fa1f5 100644
--- a/sample-2-2/sample-2-2-jdbc-spring/pom.xml
+++ b/sample-2-2/sample-2-2-jdbc-spring/pom.xml
@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.1.2.RELEASE</version>
+		<version>2.3.1.RELEASE</version>
 		<relativePath />
 	</parent>
 
diff --git a/sample-2-2/sample-2-2-jpa-spring-data/pom.xml b/sample-2-2/sample-2-2-jpa-spring-data/pom.xml
index 3e521de..0c6b516 100644
--- a/sample-2-2/sample-2-2-jpa-spring-data/pom.xml
+++ b/sample-2-2/sample-2-2-jpa-spring-data/pom.xml
@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.1.2.RELEASE</version>
+		<version>2.3.1.RELEASE</version>
 		<relativePath />
 	</parent>
 
diff --git a/sample-2-3/sample-2-3-mongo-reactive/pom.xml b/sample-2-3/sample-2-3-mongo-reactive/pom.xml
index 416ae1f..9d6501c 100644
--- a/sample-2-3/sample-2-3-mongo-reactive/pom.xml
+++ b/sample-2-3/sample-2-3-mongo-reactive/pom.xml
@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.1.2.RELEASE</version>
+		<version>2.3.1.RELEASE</version>
 		<relativePath />
 	</parent>
 
diff --git a/sample-2-3/sample-2-3-mongo/pom.xml b/sample-2-3/sample-2-3-mongo/pom.xml
index 51beaa3..9050ed3 100644
--- a/sample-2-3/sample-2-3-mongo/pom.xml
+++ b/sample-2-3/sample-2-3-mongo/pom.xml
@@ -14,7 +14,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.1.2.RELEASE</version>
+		<version>2.3.1.RELEASE</version>
 		<relativePath />
 	</parent>
 
diff --git a/sample-3-1/pom.xml b/sample-3-1/pom.xml
index eaefd18..a20babe 100644
--- a/sample-3-1/pom.xml
+++ b/sample-3-1/pom.xml
@@ -14,7 +14,7 @@
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.1.2.RELEASE</version>
+        <version>2.3.1.RELEASE</version>
         <relativePath/>
     </parent>
 
diff --git a/sample-3-2/pom.xml b/sample-3-2/pom.xml
index ba8fafa..bd2d6ae 100644
--- a/sample-3-2/pom.xml
+++ b/sample-3-2/pom.xml
@@ -20,7 +20,7 @@
 	<parent>
 		<groupId>org.springframework.boot</groupId>
 		<artifactId>spring-boot-starter-parent</artifactId>
-		<version>2.1.2.RELEASE</version>
+		<version>2.3.1.RELEASE</version>
 		<relativePath/>
 	</parent>