diff --git a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
index 7844195..38e8ff1 100644
--- a/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
+++ b/native/jni/src/suggest/core/policy/dictionary_structure_with_buffer_policy.h
@@ -100,6 +100,8 @@
     // starts iterating the dictionary.
     virtual int getNextWordAndNextToken(const int token, int *const outCodePoints) = 0;
 
+    virtual bool isCorrupted() const = 0;
+
  protected:
     DictionaryStructureWithBufferPolicy() {}
 
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp
index fa59930..212f2ef 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.cpp
@@ -36,6 +36,7 @@
     if (nextPos < 0 || nextPos >= mDictBufferSize) {
         AKLOGE("Children PtNode array position is invalid. pos: %d, dict size: %d",
                 nextPos, mDictBufferSize);
+        mIsCorrupted = true;
         ASSERT(false);
         return;
     }
@@ -45,6 +46,7 @@
         if (nextPos < 0 || nextPos >= mDictBufferSize) {
             AKLOGE("Child PtNode position is invalid. pos: %d, dict size: %d, childCount: %d / %d",
                     nextPos, mDictBufferSize, i, childCount);
+            mIsCorrupted = true;
             ASSERT(false);
             return;
         }
@@ -239,7 +241,13 @@
         const int length, const bool forceLowerCaseSearch) const {
     DynamicPtReadingHelper readingHelper(&mPtNodeReader, &mPtNodeArrayReader);
     readingHelper.initWithPtNodeArrayPos(getRootPosition());
-    return readingHelper.getTerminalPtNodePositionOfWord(inWord, length, forceLowerCaseSearch);
+    const int ptNodePos =
+            readingHelper.getTerminalPtNodePositionOfWord(inWord, length, forceLowerCaseSearch);
+    if (readingHelper.isError()) {
+        mIsCorrupted = true;
+        AKLOGE("Dictionary reading error in createAndGetAllChildDicNodes().");
+    }
+    return ptNodePos;
 }
 
 int PatriciaTriePolicy::getProbability(const int unigramProbability,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
index 8fbca26..6a2345a 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v2/patricia_trie_policy.h
@@ -46,7 +46,7 @@
               mBigramListPolicy(mDictRoot), mShortcutListPolicy(mDictRoot),
               mPtNodeReader(mDictRoot, mDictBufferSize, &mBigramListPolicy, &mShortcutListPolicy),
               mPtNodeArrayReader(mDictRoot, mDictBufferSize),
-              mTerminalPtNodePositionsForIteratingWords() {}
+              mTerminalPtNodePositionsForIteratingWords(), mIsCorrupted(false) {}
 
     AK_FORCE_INLINE int getRootPosition() const {
         return 0;
@@ -134,6 +134,10 @@
 
     int getNextWordAndNextToken(const int token, int *const outCodePoints);
 
+    bool isCorrupted() const {
+        return mIsCorrupted;
+    }
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(PatriciaTriePolicy);
 
@@ -146,6 +150,7 @@
     const Ver2ParticiaTrieNodeReader mPtNodeReader;
     const Ver2PtNodeArrayReader mPtNodeArrayReader;
     std::vector<int> mTerminalPtNodePositionsForIteratingWords;
+    mutable bool mIsCorrupted;
 
     int createAndGetLeavingChildNode(const DicNode *const dicNode, const int ptNodePos,
             DicNodeVector *const childDicNodes) const;
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
index efc29a0..b5d80be 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.cpp
@@ -65,6 +65,10 @@
                 ptNodeParams.getCodePointCount(), ptNodeParams.getCodePoints());
         readingHelper.readNextSiblingNode(ptNodeParams);
     }
+    if (readingHelper.isError()) {
+        mIsCorrupted = true;
+        AKLOGE("Dictionary reading error in createAndGetAllChildDicNodes().");
+    }
 }
 
 int Ver4PatriciaTriePolicy::getCodePointsAndProbabilityAndReturnCodePointCount(
@@ -72,15 +76,26 @@
         int *const outUnigramProbability) const {
     DynamicPtReadingHelper readingHelper(&mNodeReader, &mPtNodeArrayReader);
     readingHelper.initWithPtNodePos(ptNodePos);
-    return readingHelper.getCodePointsAndProbabilityAndReturnCodePointCount(
+    const int codePointCount =  readingHelper.getCodePointsAndProbabilityAndReturnCodePointCount(
             maxCodePointCount, outCodePoints, outUnigramProbability);
+    if (readingHelper.isError()) {
+        mIsCorrupted = true;
+        AKLOGE("Dictionary reading error in getCodePointsAndProbabilityAndReturnCodePointCount().");
+    }
+    return codePointCount;
 }
 
 int Ver4PatriciaTriePolicy::getTerminalPtNodePositionOfWord(const int *const inWord,
         const int length, const bool forceLowerCaseSearch) const {
     DynamicPtReadingHelper readingHelper(&mNodeReader, &mPtNodeArrayReader);
     readingHelper.initWithPtNodeArrayPos(getRootPosition());
-    return readingHelper.getTerminalPtNodePositionOfWord(inWord, length, forceLowerCaseSearch);
+    const int ptNodePos =
+            readingHelper.getTerminalPtNodePositionOfWord(inWord, length, forceLowerCaseSearch);
+    if (readingHelper.isError()) {
+        mIsCorrupted = true;
+        AKLOGE("Dictionary reading error in createAndGetAllChildDicNodes().");
+    }
+    return ptNodePos;
 }
 
 int Ver4PatriciaTriePolicy::getProbability(const int unigramProbability,
@@ -265,7 +280,10 @@
         AKLOGI("Warning: flush() is called for non-updatable dictionary. filePath: %s", filePath);
         return;
     }
-    mWritingHelper.writeToDictFile(filePath, mUnigramCount, mBigramCount);
+    if (!mWritingHelper.writeToDictFile(filePath, mUnigramCount, mBigramCount)) {
+        AKLOGE("Cannot flush the dictionary to file.");
+        mIsCorrupted = true;
+    }
 }
 
 void Ver4PatriciaTriePolicy::flushWithGC(const char *const filePath) {
@@ -273,7 +291,10 @@
         AKLOGI("Warning: flushWithGC() is called for non-updatable dictionary.");
         return;
     }
-    mWritingHelper.writeToDictFileWithGC(getRootPosition(), filePath);
+    if (!mWritingHelper.writeToDictFileWithGC(getRootPosition(), filePath)) {
+        AKLOGE("Cannot flush the dictionary to file with GC.");
+        mIsCorrupted = true;
+    }
 }
 
 bool Ver4PatriciaTriePolicy::needsToRunGC(const bool mindsBlockByGC) const {
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
index 6921630..7796e2d 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_policy.h
@@ -55,7 +55,7 @@
               mWritingHelper(mBuffers.get()),
               mUnigramCount(mHeaderPolicy->getUnigramCount()),
               mBigramCount(mHeaderPolicy->getBigramCount()),
-              mTerminalPtNodePositionsForIteratingWords() {};
+              mTerminalPtNodePositionsForIteratingWords(), mIsCorrupted(false) {};
 
     AK_FORCE_INLINE int getRootPosition() const {
         return 0;
@@ -116,6 +116,10 @@
 
     int getNextWordAndNextToken(const int token, int *const outCodePoints);
 
+    bool isCorrupted() const {
+        return mIsCorrupted;
+    }
+
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTriePolicy);
 
@@ -141,6 +145,7 @@
     int mUnigramCount;
     int mBigramCount;
     std::vector<int> mTerminalPtNodePositionsForIteratingWords;
+    mutable bool mIsCorrupted;
 };
 } // namespace latinime
 #endif // LATINIME_VER4_PATRICIA_TRIE_POLICY_H
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
index acf0991..93053c3 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.cpp
@@ -33,7 +33,7 @@
 
 namespace latinime {
 
-void Ver4PatriciaTrieWritingHelper::writeToDictFile(const char *const dictDirPath,
+bool Ver4PatriciaTrieWritingHelper::writeToDictFile(const char *const dictDirPath,
         const int unigramCount, const int bigramCount) const {
     const HeaderPolicy *const headerPolicy = mBuffers->getHeaderPolicy();
     BufferWithExtendableBuffer headerBuffer(
@@ -46,12 +46,12 @@
                 "updatesLastDecayedTime: %d, unigramCount: %d, bigramCount: %d, "
                 "extendedRegionSize: %d", false, unigramCount, bigramCount,
                 extendedRegionSize);
-        return;
+        return false;
     }
-    mBuffers->flushHeaderAndDictBuffers(dictDirPath, &headerBuffer);
+    return mBuffers->flushHeaderAndDictBuffers(dictDirPath, &headerBuffer);
 }
 
-void Ver4PatriciaTrieWritingHelper::writeToDictFileWithGC(const int rootPtNodeArrayPos,
+bool Ver4PatriciaTrieWritingHelper::writeToDictFileWithGC(const int rootPtNodeArrayPos,
         const char *const dictDirPath) {
     const HeaderPolicy *const headerPolicy = mBuffers->getHeaderPolicy();
     Ver4DictBuffers::Ver4DictBuffersPtr dictBuffers(
@@ -59,15 +59,15 @@
     int unigramCount = 0;
     int bigramCount = 0;
     if (!runGC(rootPtNodeArrayPos, headerPolicy, dictBuffers.get(), &unigramCount, &bigramCount)) {
-        return;
+        return false;
     }
     BufferWithExtendableBuffer headerBuffer(
             BufferWithExtendableBuffer::DEFAULT_MAX_ADDITIONAL_BUFFER_SIZE);
     if (!headerPolicy->fillInAndWriteHeaderToBuffer(true /* updatesLastDecayedTime */,
             unigramCount, bigramCount, 0 /* extendedRegionSize */, &headerBuffer)) {
-        return;
+        return false;
     }
-    dictBuffers.get()->flushHeaderAndDictBuffers(dictDirPath, &headerBuffer);
+    return dictBuffers.get()->flushHeaderAndDictBuffers(dictDirPath, &headerBuffer);
 }
 
 bool Ver4PatriciaTrieWritingHelper::runGC(const int rootPtNodeArrayPos,
diff --git a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
index c3a155e..bb464ad 100644
--- a/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
+++ b/native/jni/src/suggest/policyimpl/dictionary/structure/v4/ver4_patricia_trie_writing_helper.h
@@ -33,10 +33,12 @@
     Ver4PatriciaTrieWritingHelper(Ver4DictBuffers *const buffers)
             : mBuffers(buffers) {}
 
-    void writeToDictFile(const char *const dictDirPath, const int unigramCount,
+    bool writeToDictFile(const char *const dictDirPath, const int unigramCount,
             const int bigramCount) const;
 
-    void writeToDictFileWithGC(const int rootPtNodeArrayPos, const char *const dictDirPath);
+    // This method cannot be const because the original dictionary buffer will be updated to detect
+    // useless PtNodes during GC.
+    bool writeToDictFileWithGC(const int rootPtNodeArrayPos, const char *const dictDirPath);
 
  private:
     DISALLOW_IMPLICIT_CONSTRUCTORS(Ver4PatriciaTrieWritingHelper);