diff --git a/README.md b/README.md
index 208df17d..71dcbe99 100644
--- a/README.md
+++ b/README.md
@@ -561,18 +561,18 @@ public class ConcurrencyStrategyDemo {
     <dependency>
       <groupId>io.foldright</groupId>
       <artifactId>cffu</artifactId>
-      <version>1.0.0-Alpha1</version>
+      <version>1.0.0-Alpha2</version>
     </dependency>
     ```
   - For `Gradle` projects:
 
     ```groovy
     // Gradle Kotlin DSL
-    implementation("io.foldright:cffu:1.0.0-Alpha1")
+    implementation("io.foldright:cffu:1.0.0-Alpha2")
     ```
     ```groovy
     // Gradle Groovy DSL
-    implementation 'io.foldright:cffu:1.0.0-Alpha1'
+    implementation 'io.foldright:cffu:1.0.0-Alpha2'
     ```
 - `cffu Kotlin`支持库:
   - For `Maven` projects:
@@ -581,18 +581,18 @@ public class ConcurrencyStrategyDemo {
     <dependency>
       <groupId>io.foldright</groupId>
       <artifactId>cffu-kotlin</artifactId>
-      <version>1.0.0-Alpha1</version>
+      <version>1.0.0-Alpha2</version>
     </dependency>
     ```
   - For `Gradle` projects:
 
     ```groovy
     // Gradle Kotlin DSL
-    implementation("io.foldright:cffu-kotlin:1.0.0-Alpha1")
+    implementation("io.foldright:cffu-kotlin:1.0.0-Alpha2")
     ```
     ```groovy
     // Gradle Groovy DSL
-    implementation 'io.foldright:cffu-kotlin:1.0.0-Alpha1'
+    implementation 'io.foldright:cffu-kotlin:1.0.0-Alpha2'
     ```
 - `cffu bom`:
   - For `Maven` projects:
@@ -601,7 +601,7 @@ public class ConcurrencyStrategyDemo {
     <dependency>
       <groupId>io.foldright</groupId>
       <artifactId>cffu-bom</artifactId>
-      <version>1.0.0-Alpha1</version>
+      <version>1.0.0-Alpha2</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -610,11 +610,11 @@ public class ConcurrencyStrategyDemo {
 
     ```groovy
     // Gradle Kotlin DSL
-    implementation(platform("io.foldright:cffu-bom:1.0.0-Alpha1"))
+    implementation(platform("io.foldright:cffu-bom:1.0.0-Alpha2"))
     ```
     ```groovy
     // Gradle Groovy DSL
-    implementation platform('io.foldright:cffu-bom:1.0.0-Alpha1')
+    implementation platform('io.foldright:cffu-bom:1.0.0-Alpha2')
     ```
 - [📌 `TransmittableThreadLocal(TTL)`](https://github.com/alibaba/transmittable-thread-local)的[`cffu executor wrapper SPI`实现](cffu-ttl-executor-wrapper)：
   - For `Maven` projects:
@@ -623,7 +623,7 @@ public class ConcurrencyStrategyDemo {
     <dependency>
       <groupId>io.foldright</groupId>
       <artifactId>cffu-ttl-executor-wrapper</artifactId>
-      <version>1.0.0-Alpha1</version>
+      <version>1.0.0-Alpha2</version>
       <scope>runtime</scope>
     </dependency>
     ```
@@ -631,11 +631,11 @@ public class ConcurrencyStrategyDemo {
 
     ```groovy
     // Gradle Kotlin DSL
-    runtimeOnly("io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha1")
+    runtimeOnly("io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha2")
     ```
     ```groovy
     // Gradle Groovy DSL
-    runtimeOnly 'io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha1'
+    runtimeOnly 'io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha2'
     ```
 
 # 📚 更多资料
diff --git a/cffu-core/src/main/java/io/foldright/cffu/CffuFactory.java b/cffu-core/src/main/java/io/foldright/cffu/CffuFactory.java
index f6c6d0ee..72ace5f5 100644
--- a/cffu-core/src/main/java/io/foldright/cffu/CffuFactory.java
+++ b/cffu-core/src/main/java/io/foldright/cffu/CffuFactory.java
@@ -255,6 +255,7 @@ public <T> Cffu<T> newIncompleteCffu() {
      * <li>otherwise use input {@code stage.toCompletableFuture} as the underlying cf of returned cffu.
      * </ol>
      *
+     * @throws NullPointerException if the given stage is null
      * @see #toCffuArray(CompletionStage[])
      * @see CompletionStage#toCompletableFuture()
      * @see Cffu#cffuUnwrap()
@@ -278,11 +279,13 @@ public <T> Cffu<T> toCffu(CompletionStage<T> stage) {
      * A convenient util method for wrap input {@link CompletableFuture} / {@link CompletionStage} / {@link Cffu}
      * array element by {@link #toCffu(CompletionStage)}.
      *
+     * @throws NullPointerException if the array or any of its elements are {@code null}
      * @see #toCffu(CompletionStage)
      */
     @Contract(pure = true)
     @SafeVarargs
     public final <T> Cffu<T>[] toCffuArray(CompletionStage<T>... stages) {
+        requireNonNull(stages, "stages is null");
         @SuppressWarnings("unchecked")
         Cffu<T>[] ret = new Cffu[stages.length];
         for (int i = 0; i < stages.length; i++) {
diff --git a/cffu-core/src/main/java/io/foldright/cffu/CompletableFutureUtils.java b/cffu-core/src/main/java/io/foldright/cffu/CompletableFutureUtils.java
index fc43455f..4bbd4dd7 100644
--- a/cffu-core/src/main/java/io/foldright/cffu/CompletableFutureUtils.java
+++ b/cffu-core/src/main/java/io/foldright/cffu/CompletableFutureUtils.java
@@ -1029,6 +1029,7 @@ public static <T> CompletableFuture<T> failedFuture(Throwable ex) {
         if (IS_JAVA9_PLUS) {
             return CompletableFuture.failedFuture(ex);
         }
+        requireNonNull(ex, "ex is null");
         final CompletableFuture<T> cf = new CompletableFuture<>();
         cf.completeExceptionally(ex);
         return cf;
@@ -1215,7 +1216,6 @@ public static <T> CompletableFuture<T> exceptionallyCompose(
         if (IS_JAVA12_PLUS) {
             return cf.exceptionallyCompose(fn);
         }
-
         requireNonNull(fn, "fn is null");
         // below code is copied from CompletionStage.exceptionallyCompose
         return cf.handle((r, ex) -> (ex == null) ? cf : fn.apply(ex)).thenCompose(identity());
@@ -1249,7 +1249,6 @@ public static <T> CompletableFuture<T> exceptionallyComposeAsync(
         if (IS_JAVA12_PLUS) {
             return cf.exceptionallyComposeAsync(fn, executor);
         }
-
         requireNonNull(fn, "fn is null");
         requireNonNull(executor, "executor is null");
         // below code is copied from CompletionStage.exceptionallyComposeAsync
@@ -1294,7 +1293,6 @@ public static <T> CompletableFuture<T> exceptionallyComposeAsync(
     @Nullable
     public static <T> T join(CompletableFuture<T> cf, long timeout, TimeUnit unit) {
         if (cf.isDone()) return cf.join();
-
         return orTimeout(copy(cf), timeout, unit).join();
     }
 
@@ -1536,6 +1534,7 @@ public static Executor defaultExecutor() {
     @Contract(pure = true)
     @SafeVarargs
     public static <T> CompletableFuture<T>[] toCompletableFutureArray(CompletionStage<T>... stages) {
+        requireNonNull(stages, "stages is null");
         @SuppressWarnings("unchecked")
         CompletableFuture<T>[] ret = new CompletableFuture[stages.length];
         for (int i = 0; i < stages.length; i++) {
diff --git a/cffu-ttl-executor-wrapper/README.md b/cffu-ttl-executor-wrapper/README.md
index 50dcf9e8..abc2cd9a 100644
--- a/cffu-ttl-executor-wrapper/README.md
+++ b/cffu-ttl-executor-wrapper/README.md
@@ -18,7 +18,7 @@ For `Maven` projects:
   <groupId>io.foldright</groupId>
   <artifactId>cffu-ttl-executor-wrapper</artifactId>
   <scope>runtime</scope>
-  <version>1.0.0-Alpha1</version>
+  <version>1.0.0-Alpha2</version>
 </dependency>
 ```
 
@@ -26,12 +26,12 @@ For `Gradle` projects:
 
 ```groovy
 // Gradle Kotlin DSL
-runtimeOnly("io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha1")
+runtimeOnly("io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha2")
 ```
 
 ```groovy
 // Gradle Groovy DSL
-runtimeOnly 'io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha1'
+runtimeOnly 'io.foldright:cffu-ttl-executor-wrapper:1.0.0-Alpha2'
 ```
 
 `cffu-ttl-executor-wrapper` has published to maven central, find the latest version at