diff --git a/google-cloud-pubsublite-bom/pom.xml b/google-cloud-pubsublite-bom/pom.xml
index 5338466e7..88df457e6 100644
--- a/google-cloud-pubsublite-bom/pom.xml
+++ b/google-cloud-pubsublite-bom/pom.xml
@@ -3,7 +3,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-pubsublite-bom</artifactId>
-  <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+  <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
   <packaging>pom</packaging>
   <parent>
     <groupId>com.google.cloud</groupId>
@@ -52,17 +52,17 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-pubsublite</artifactId>
-        <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+        <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-pubsublite-v1</artifactId>
-        <version>1.15.20</version><!-- {x-version-update:grpc-google-cloud-pubsublite-v1:current} -->
+        <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:grpc-google-cloud-pubsublite-v1:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-pubsublite-v1</artifactId>
-        <version>1.15.20</version><!-- {x-version-update:proto-google-cloud-pubsublite-v1:current} -->
+        <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:proto-google-cloud-pubsublite-v1:current} -->
       </dependency>
     </dependencies>
   </dependencyManagement>
diff --git a/google-cloud-pubsublite/pom.xml b/google-cloud-pubsublite/pom.xml
index addd452f4..e9a212bf9 100644
--- a/google-cloud-pubsublite/pom.xml
+++ b/google-cloud-pubsublite/pom.xml
@@ -3,13 +3,13 @@
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-pubsublite-parent</artifactId>
-    <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+    <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
     <relativePath>../pom.xml</relativePath>
   </parent>
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-pubsublite</artifactId>
-  <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+  <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
   <packaging>jar</packaging>
   <name>Google Cloud Pub/Sub Lite</name>
   <url>https://github.com/googleapis/java-pubsublite</url>
@@ -48,12 +48,12 @@
     <dependency>
       <groupId>com.google.api.grpc</groupId>
       <artifactId>proto-google-cloud-pubsublite-v1</artifactId>
-      <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+      <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
     </dependency>
     <dependency>
       <groupId>com.google.api.grpc</groupId>
       <artifactId>grpc-google-cloud-pubsublite-v1</artifactId>
-      <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+      <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
     </dependency>
     <dependency>
       <groupId>com.google.flogger</groupId>
diff --git a/grpc-google-cloud-pubsublite-v1/pom.xml b/grpc-google-cloud-pubsublite-v1/pom.xml
index 8bcee90ae..5c46121e0 100644
--- a/grpc-google-cloud-pubsublite-v1/pom.xml
+++ b/grpc-google-cloud-pubsublite-v1/pom.xml
@@ -4,20 +4,20 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>grpc-google-cloud-pubsublite-v1</artifactId>
-  <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+  <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
   <name>grpc-google-cloud-pubsublite-v1</name>
   <description>GRPC library for grpc-google-cloud-pubsublite-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-pubsublite-parent</artifactId>
-    <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+    <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
     <relativePath>../pom.xml</relativePath>
   </parent>
   <dependencies>
     <dependency>
       <groupId>com.google.api.grpc</groupId>
       <artifactId>proto-google-cloud-pubsublite-v1</artifactId>
-      <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+      <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
     </dependency>
     <dependency>
       <groupId>io.grpc</groupId>
diff --git a/pom.xml b/pom.xml
index dcd8ab061..79703eb08 100644
--- a/pom.xml
+++ b/pom.xml
@@ -8,7 +8,7 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-pubsublite-parent</artifactId>
-  <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+  <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
   <packaging>pom</packaging>
   <name>Google Cloud Pub/Sub Lite Parent</name>
   <url>https://github.com/googleapis/java-pubsublite</url>
@@ -25,17 +25,17 @@
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>proto-google-cloud-pubsublite-v1</artifactId>
-        <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+        <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.api.grpc</groupId>
         <artifactId>grpc-google-cloud-pubsublite-v1</artifactId>
-        <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+        <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-pubsublite</artifactId>
-        <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+        <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
       </dependency>
       <dependency>
         <groupId>com.google.auto.service</groupId>
diff --git a/proto-google-cloud-pubsublite-v1/pom.xml b/proto-google-cloud-pubsublite-v1/pom.xml
index 00b073d59..631c9e02e 100644
--- a/proto-google-cloud-pubsublite-v1/pom.xml
+++ b/proto-google-cloud-pubsublite-v1/pom.xml
@@ -4,13 +4,13 @@
   <modelVersion>4.0.0</modelVersion>
   <groupId>com.google.api.grpc</groupId>
   <artifactId>proto-google-cloud-pubsublite-v1</artifactId>
-  <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+  <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
   <name>proto-google-cloud-pubsublite-v1</name>
   <description>PROTO library for proto-google-cloud-pubsublite-v1</description>
   <parent>
     <groupId>com.google.cloud</groupId>
     <artifactId>google-cloud-pubsublite-parent</artifactId>
-    <version>1.15.20</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
+    <version>1.15.21-SNAPSHOT</version><!-- {x-version-update:google-cloud-pubsublite:current} -->
     <relativePath>../pom.xml</relativePath>
   </parent>
   <dependencies>
diff --git a/samples/snapshot/pom.xml b/samples/snapshot/pom.xml
index 1e87e82c6..ccd49fd22 100644
--- a/samples/snapshot/pom.xml
+++ b/samples/snapshot/pom.xml
@@ -45,7 +45,7 @@
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>google-cloud-pubsublite</artifactId>
-      <version>1.15.20</version>
+      <version>1.15.21-SNAPSHOT</version>
     </dependency>
     <!-- {x-version-update-end} -->
     <dependency>
diff --git a/versions.txt b/versions.txt
index 239e49e92..1f0e4286d 100644
--- a/versions.txt
+++ b/versions.txt
@@ -1,7 +1,7 @@
 # Format:
 # module:released-version:current-version
 
-google-cloud-pubsublite:1.15.20:1.15.20
-pubsublite-beam-io:0.34.20:0.34.20
-proto-google-cloud-pubsublite-v1:1.15.20:1.15.20
-grpc-google-cloud-pubsublite-v1:1.15.20:1.15.20
+google-cloud-pubsublite:1.15.20:1.15.21-SNAPSHOT
+pubsublite-beam-io:0.34.20:0.34.21-SNAPSHOT
+proto-google-cloud-pubsublite-v1:1.15.20:1.15.21-SNAPSHOT
+grpc-google-cloud-pubsublite-v1:1.15.20:1.15.21-SNAPSHOT