diff --git a/NEWS.md b/NEWS.md
index e7574cec..14b05243 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -25,6 +25,7 @@ Red Panda C++ Version 2.26
   - enhancement: Slightly reduce memory usage.
   - change: In Options -> Language -> Generate Assembly, option "Don't generate SEH directives" default to True.
   - change: In Options —> Editor -> Code Suggestion, option "Hide symbols starting with underscore" default to True.
+  - fix: Crash if include a non-exist header file in the source.
 
 Red Panda C++ Version 2.25
 
diff --git a/RedPandaIDE/compiler/projectcompiler.cpp b/RedPandaIDE/compiler/projectcompiler.cpp
index 56ab9e6c..a1e2ef36 100644
--- a/RedPandaIDE/compiler/projectcompiler.cpp
+++ b/RedPandaIDE/compiler/projectcompiler.cpp
@@ -358,8 +358,8 @@ void ProjectCompiler::writeMakeObjFilesRules(QFile &file)
         writeln(file);
         QString objStr=genMakePath2(shortFileName);
         // if we have scanned it, use scanned info
-        if (parser && parser->scannedFiles().contains(unit->fileName())) {
-            QSet<QString> fileIncludes = parser->getFileIncludes(unit->fileName());
+        if (parser && parser->fileScanned(unit->fileName())) {
+            QSet<QString> fileIncludes = parser->getIncludedFiles(unit->fileName());
             foreach(const PProjectUnit &unit2, projectUnits) {
                 if (unit2==unit)
                     continue;
diff --git a/RedPandaIDE/compiler/sdccprojectcompiler.cpp b/RedPandaIDE/compiler/sdccprojectcompiler.cpp
index e360985e..d471dadb 100644
--- a/RedPandaIDE/compiler/sdccprojectcompiler.cpp
+++ b/RedPandaIDE/compiler/sdccprojectcompiler.cpp
@@ -235,8 +235,8 @@ void SDCCProjectCompiler::writeMakeObjFilesRules(QFile &file)
         writeln(file);
         QString objStr=genMakePath2(shortFileName);
         // if we have scanned it, use scanned info
-        if (parser && parser->scannedFiles().contains(unit->fileName())) {
-            QSet<QString> fileIncludes = parser->getFileIncludes(unit->fileName());
+        if (parser && parser->fileScanned(unit->fileName())) {
+            QSet<QString> fileIncludes = parser->getIncludedFiles(unit->fileName());
             foreach(const PProjectUnit &unit2, projectUnits) {
                 if (unit2==unit)
                     continue;
diff --git a/RedPandaIDE/parser/cppparser.cpp b/RedPandaIDE/parser/cppparser.cpp
index 9cb96d5f..62e11711 100644
--- a/RedPandaIDE/parser/cppparser.cpp
+++ b/RedPandaIDE/parser/cppparser.cpp
@@ -187,7 +187,7 @@ PStatement CppParser::findScopeStatement(const QString &filename, int line)
 
 PStatement CppParser::doFindScopeStatement(const QString &filename, int line) const
 {
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(filename);
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(filename);
     if (!fileIncludes)
         return PStatement();
 
@@ -197,9 +197,9 @@ PStatement CppParser::doFindScopeStatement(const QString &filename, int line) co
 PFileIncludes CppParser::findFileIncludes(const QString &filename, bool deleteIt)
 {
     QMutexLocker locker(&mMutex);
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(filename,PFileIncludes());
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(filename);
     if (deleteIt && fileIncludes)
-        mPreprocessor.includesList().remove(filename);
+        mPreprocessor.removeFileIncludes(filename);
     return fileIncludes;
 }
 QString CppParser::findFirstTemplateParamOf(const QString &fileName, const QString &phrase, const PStatement& currentScope)
@@ -221,7 +221,7 @@ QString CppParser::findTemplateParamOf(const QString &fileName, const QString &p
 PStatement CppParser::findFunctionAt(const QString &fileName, int line)
 {
     QMutexLocker locker(&mMutex);
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(fileName);
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(fileName);
     if (!fileIncludes)
         return PStatement();
     for (PStatement& statement : fileIncludes->statements) {
@@ -775,7 +775,7 @@ QStringList CppParser::getFileDirectIncludes(const QString &filename)
         return QStringList();
     if (filename.isEmpty())
         return QStringList();
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(filename,PFileIncludes());
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(filename);
 
     if (fileIncludes) {
         return fileIncludes->directIncludes;
@@ -784,7 +784,7 @@ QStringList CppParser::getFileDirectIncludes(const QString &filename)
 
 }
 
-QSet<QString> CppParser::getFileIncludes(const QString &filename)
+QSet<QString> CppParser::getIncludedFiles(const QString &filename)
 {
     QMutexLocker locker(&mMutex);
     QSet<QString> list;
@@ -793,7 +793,7 @@ QSet<QString> CppParser::getFileIncludes(const QString &filename)
     if (filename.isEmpty())
         return list;
     list.insert(filename);
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(filename,PFileIncludes());
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(filename);
 
     if (fileIncludes) {
         foreach (const QString& file, fileIncludes->includeFiles.keys()) {
@@ -816,13 +816,13 @@ QSet<QString> CppParser::internalGetFileUsings(const QString &filename) const
         return result;
 //    if (mParsing)
 //        return result;
-    PFileIncludes fileIncludes= mPreprocessor.includesList().value(filename,PFileIncludes());
+    PFileIncludes fileIncludes= mPreprocessor.findFileIncludes(filename);
     if (fileIncludes) {
         foreach (const QString& usingName, fileIncludes->usings) {
             result.insert(usingName);
         }
         foreach (const QString& subFile,fileIncludes->includeFiles.keys()){
-            PFileIncludes subIncludes = mPreprocessor.includesList().value(subFile,PFileIncludes());
+            PFileIncludes subIncludes = mPreprocessor.findFileIncludes(subFile);
             if (subIncludes) {
                 foreach (const QString& usingName, subIncludes->usings) {
                     result.insert(usingName);
@@ -872,7 +872,7 @@ bool CppParser::isLineVisible(const QString &fileName, int line)
     if (mParsing) {
         return true;
     }
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(fileName);
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(fileName);
     if (!fileIncludes)
         return true;
     return fileIncludes->isLineVisible(line);
@@ -952,7 +952,7 @@ void CppParser::parseFile(const QString &fileName, bool inProject, bool onlyIfNo
                 emit onEndParsing(mFilesScannedCount,0);
         });
         QString fName = fileName;
-        if (onlyIfNotParsed && mPreprocessor.scannedFiles().contains(fName))
+        if (onlyIfNotParsed && mPreprocessor.fileScanned(fName))
             return;
 
         if (inProject) {
@@ -966,7 +966,7 @@ void CppParser::parseFile(const QString &fileName, bool inProject, bool onlyIfNo
             foreach (const QString& file,files) {
                 mFilesScannedCount++;
                 emit onProgress(file,mFilesToScanCount,mFilesScannedCount);
-                if (!mPreprocessor.scannedFiles().contains(file)) {
+                if (!mPreprocessor.fileScanned(file)) {
                     internalParse(file);
                 }
             }
@@ -1022,7 +1022,7 @@ void CppParser::parseFileList(bool updateView)
         foreach (const QString& file, files) {
             mFilesScannedCount++;
             emit onProgress(mCurrentFile,mFilesToScanCount,mFilesScannedCount);
-            if (!mPreprocessor.scannedFiles().contains(file)) {
+            if (!mPreprocessor.fileScanned(file)) {
                 internalParse(file);
             }
         }
@@ -1119,14 +1119,17 @@ void CppParser::unFreeze()
     mLockCount--;
 }
 
-QSet<QString> CppParser::scannedFiles()
+bool CppParser::fileScanned(const QString &fileName)
 {
-    return mPreprocessor.scannedFiles();
+    QMutexLocker locker(&mMutex);
+    if (mParsing)
+        return false;
+    return mPreprocessor.fileScanned(fileName);
 }
 
 bool CppParser::isFileParsed(const QString &filename)
 {
-    return mPreprocessor.scannedFiles().contains(filename);
+    return mPreprocessor.fileScanned(filename);
 }
 
 QString CppParser::getScopePrefix(const PStatement& statement) const{
@@ -1280,7 +1283,7 @@ void CppParser::addProjectFile(const QString &fileName, bool needScan)
         mProjectFiles.insert(fileName);
 
     // Only parse given file
-    if (needScan && !mPreprocessor.scannedFiles().contains(fileName)) {
+    if (needScan && !mPreprocessor.fileScanned(fileName)) {
         mFilesToScan.insert(fileName);
     }
 }
@@ -1362,7 +1365,7 @@ PStatement CppParser::addStatement(const PStatement& parent,
             if (oldStatement  && !oldStatement->hasDefinition()) {
                 oldStatement->setHasDefinition(true);
                 if (oldStatement->fileName!=fileName) {
-                    PFileIncludes fileIncludes=mPreprocessor.includesList().value(fileName);
+                    PFileIncludes fileIncludes=mPreprocessor.findFileIncludes(fileName);
                     if (fileIncludes) {
                         fileIncludes->statements.insert(oldStatement->fullName,
                                                          oldStatement);
@@ -1424,7 +1427,7 @@ PStatement CppParser::addStatement(const PStatement& parent,
     }
 
     if (result->kind!= StatementKind::skBlock) {
-        PFileIncludes fileIncludes = mPreprocessor.includesList().value(fileName);
+        PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(fileName);
         if (fileIncludes) {
             fileIncludes->statements.insert(result->fullName,result);
         }
@@ -1663,7 +1666,7 @@ void CppParser::addSoloScopeLevel(PStatement& statement, int line, bool shouldRe
 
     mCurrentScope.append(statement);
 
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(mCurrentFile);
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(mCurrentFile);
 
     if (fileIncludes) {
         fileIncludes->scopes.addScope(line,statement);
@@ -1695,17 +1698,17 @@ void CppParser::removeScopeLevel(int line)
 //        qDebug()<<"--remove scope"<<mCurrentFile<<line<<mCurrentClassScope.count();
 #endif
     PStatement currentScope = getCurrentScope();
-    PFileIncludes fileIncludes = mPreprocessor.includesList().value(mCurrentFile);
+    PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(mCurrentFile);
     if (currentScope) {
         if (currentScope->kind == StatementKind::skBlock) {
             if (currentScope->children.isEmpty()) {
                 // remove no children block
-                if (fileIncludes) {
+                if (fileIncludes)
                     fileIncludes->scopes.removeLastScope();
-                }
                 mStatementList.deleteStatement(currentScope);
             } else {
-                fileIncludes->statements.insert(currentScope->fullName,currentScope);
+                if (fileIncludes)
+                    fileIncludes->statements.insert(currentScope->fullName,currentScope);
             }
         } else if (currentScope->kind == StatementKind::skClass) {
             mIndex=indexOfNextSemicolon(mIndex);
@@ -1742,13 +1745,11 @@ void CppParser::internalClear()
 QStringList CppParser::sortFilesByIncludeRelations(const QSet<QString> &files)
 {
     QStringList result;
-    QSet<QString> saveScannedFiles;
-
-    saveScannedFiles=mPreprocessor.scannedFiles();
+    QSet<QString> saveScannedFiles{mPreprocessor.scannedFiles()};
 
     //rebuild file include relations
     foreach(const QString& file, files) {
-        if (mPreprocessor.scannedFiles().contains(file))
+        if (mPreprocessor.fileScanned(file))
             continue;
         //already removed in interalInvalidateFiles
         //mPreprocessor.removeScannedFile(file);
@@ -1762,12 +1763,14 @@ QStringList CppParser::sortFilesByIncludeRelations(const QSet<QString> &files)
     while (!fileSet.isEmpty()) {
         bool found=false;
         foreach (const QString& file,fileSet) {
-            PFileIncludes fileIncludes = mPreprocessor.includesList().value(file);
+            PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(file);
             bool hasInclude=false;
-            foreach(const QString& inc,fileIncludes->includeFiles.keys()) {
-                if (fileSet.contains(inc)) {
-                    hasInclude=true;
-                    break;
+            if (fileIncludes) {
+                foreach(const QString& inc,fileIncludes->includeFiles.keys()) {
+                    if (fileSet.contains(inc)) {
+                        hasInclude=true;
+                        break;
+                    }
                 }
             }
             if (!hasInclude) {
@@ -1784,7 +1787,7 @@ QStringList CppParser::sortFilesByIncludeRelations(const QSet<QString> &files)
             }
         }
     }
-    QSet<QString> newScannedFiles = mPreprocessor.scannedFiles();
+    QSet<QString> newScannedFiles{mPreprocessor.scannedFiles()};
     foreach(const QString& file, newScannedFiles) {
         if (!saveScannedFiles.contains(file))
             mPreprocessor.removeScannedFile(file);
@@ -3454,7 +3457,7 @@ void CppParser::handlePreprocessor()
         if (delimPos>=0) {
 //            qDebug()<<mCurrentScope.size()<<mCurrentFile<<mTokenizer[mIndex]->line<<s.mid(0,delimPos).trimmed();
             mCurrentFile = s.mid(0,delimPos).trimmed();
-            PFileIncludes fileIncludes = mPreprocessor.includesList().value(mCurrentFile);
+            PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(mCurrentFile);
             if (fileIncludes) {
                 mCurrentFile = fileIncludes->baseFile;
             } else {
@@ -4061,7 +4064,7 @@ void CppParser::handleUsing()
             scopeStatement->usingList.insert(fullName);
         }
     } else {
-        PFileIncludes fileInfo = mPreprocessor.includesList().value(mCurrentFile);
+        PFileIncludes fileInfo = mPreprocessor.findFileIncludes(mCurrentFile);
         if (!fileInfo)
             return;
         if (mNamespaces.contains(usingName)) {
@@ -4538,7 +4541,7 @@ PStatement CppParser::findMacro(const QString &phrase, const QString &fileName)
     if (statementMap.isEmpty())
         return PStatement();
     StatementList statements = statementMap.values(phrase);
-    PFileIncludes includes = mPreprocessor.includesList().value(fileName,PFileIncludes());
+    PFileIncludes includes = mPreprocessor.findFileIncludes(fileName);
     foreach (const PStatement& s, statements) {
         if (s->kind == StatementKind::skPreprocessor) {
             if (includes && !includes->includeFiles.contains(s->fileName)
@@ -4602,7 +4605,7 @@ PStatement CppParser::findMemberOfStatement(const QString& filename,
         return statementMap.value(s,PStatement());
     } else {
         QList<PStatement> stats = statementMap.values(s);
-        PFileIncludes fileIncludes =  mPreprocessor.includesList().value(filename,PFileIncludes());
+        PFileIncludes fileIncludes =  mPreprocessor.findFileIncludes(filename);
         foreach(const PStatement &s,stats) {
             if (s->line==-1) {
                 return s; // hard defines
@@ -5952,7 +5955,7 @@ QSet<QString> CppParser::calculateFilesToBeReparsed(const QString &fileName)
     QSet<QString> result;
     result.insert(fileName);
     foreach (const QString& file, mProjectFiles) {
-        PFileIncludes fileIncludes = mPreprocessor.includesList().value(file,PFileIncludes());
+        PFileIncludes fileIncludes = mPreprocessor.findFileIncludes(file);
         if (fileIncludes && fileIncludes->includeFiles.contains(fileName)) {
             result.insert(file);
         }
diff --git a/RedPandaIDE/parser/cppparser.h b/RedPandaIDE/parser/cppparser.h
index c05ae7cc..0327f419 100644
--- a/RedPandaIDE/parser/cppparser.h
+++ b/RedPandaIDE/parser/cppparser.h
@@ -98,7 +98,7 @@ public:
     bool freeze(const QString& serialId);  // Freeze/Lock (stop reparse while searching)
     QStringList getClassesList();
     QStringList getFileDirectIncludes(const QString& filename);
-    QSet<QString> getFileIncludes(const QString& filename);
+    QSet<QString> getIncludedFiles(const QString& filename);
     QSet<QString> getFileUsings(const QString& filename);
 
     QString getHeaderFileName(const QString& relativeTo, const QString& headerName, bool fromNext=false);// both
@@ -116,7 +116,7 @@ public:
     bool parsing() const;
     void resetParser();
     void unFreeze(); // UnFree/UnLock (reparse while searching)
-    QSet<QString> scannedFiles();
+    bool fileScanned(const QString& fileName);
 
     bool isFileParsed(const QString& filename);
 
diff --git a/RedPandaIDE/parser/cpppreprocessor.cpp b/RedPandaIDE/parser/cpppreprocessor.cpp
index 2e1749e7..e489e4a7 100644
--- a/RedPandaIDE/parser/cpppreprocessor.cpp
+++ b/RedPandaIDE/parser/cpppreprocessor.cpp
@@ -857,9 +857,11 @@ void CppPreprocessor::openInclude(QString fileName)
         //add defines of already parsed including headers;
         addDefinesInFile(fileName);
         PFileIncludes fileIncludes = getFileIncludesEntry(fileName);
-        for (PParsedFile& file:mIncludes) {
-            foreach (const QString& incFile,fileIncludes->includeFiles.keys()) {
-                file->fileIncludes->includeFiles.insert(incFile,false);
+        if (fileIncludes) {
+            for (PParsedFile& file:mIncludes) {
+                foreach (const QString& incFile,fileIncludes->includeFiles.keys()) {
+                    file->fileIncludes->includeFiles.insert(incFile,false);
+                }
             }
         }
     }
@@ -942,8 +944,10 @@ void CppPreprocessor::addDefinesInFile(const QString &fileName)
     }
 
     PFileIncludes fileIncludes = getFileIncludesEntry(fileName);
-    foreach (const QString& file, fileIncludes->includeFiles.keys()) {
-        addDefinesInFile(file);
+    if (fileIncludes) {
+        foreach (const QString& file, fileIncludes->includeFiles.keys()) {
+            addDefinesInFile(file);
+        }
     }
 }
 
@@ -2022,28 +2026,3 @@ const DefineMap &CppPreprocessor::hardDefines() const
 {
     return mHardDefines;
 }
-
-const QSet<QString> &CppPreprocessor::projectIncludePaths()
-{
-    return mProjectIncludePaths;
-}
-
-const QSet<QString> &CppPreprocessor::includePaths()
-{
-    return mIncludePaths;
-}
-
-QSet<QString> &CppPreprocessor::scannedFiles()
-{
-    return mScannedFiles;
-}
-
-QHash<QString, PFileIncludes> &CppPreprocessor::includesList()
-{
-    return mIncludesList;
-}
-
-const QHash<QString, PFileIncludes> &CppPreprocessor::includesList() const
-{
-    return mIncludesList;
-}
diff --git a/RedPandaIDE/parser/cpppreprocessor.h b/RedPandaIDE/parser/cpppreprocessor.h
index 37a9f31d..ea219f9c 100644
--- a/RedPandaIDE/parser/cpppreprocessor.h
+++ b/RedPandaIDE/parser/cpppreprocessor.h
@@ -84,15 +84,29 @@ public:
         return mResult;
     };
 
-    QHash<QString, PFileIncludes> &includesList();
+    PFileIncludes findFileIncludes(const QString& fileName) const {
+        return mIncludesList.value(fileName);
+    }
 
-    const QHash<QString, PFileIncludes> &includesList() const;
+    void removeFileIncludes(const QString& fileName) {
+        mIncludesList.remove(fileName);
+    }
 
-    QSet<QString> &scannedFiles();
+    bool fileScanned(const QString& fileName) const {
+        return mScannedFiles.contains(fileName);
+    }
 
-    const QSet<QString> &includePaths();
+    const QSet<QString>& includePaths() const {
+        return mIncludePaths;
+    }
 
-    const QSet<QString> &projectIncludePaths();
+    const QSet<QString>& scannedFiles() const {
+        return mScannedFiles;
+    }
+
+    const QSet<QString> &projectIncludePaths() {
+        return mProjectIncludePaths;
+    }
 
     const DefineMap &hardDefines() const;
 
diff --git a/RedPandaIDE/widgets/codecompletionpopup.cpp b/RedPandaIDE/widgets/codecompletionpopup.cpp
index 17385755..5f94f302 100644
--- a/RedPandaIDE/widgets/codecompletionpopup.cpp
+++ b/RedPandaIDE/widgets/codecompletionpopup.cpp
@@ -98,15 +98,15 @@ void CodeCompletionPopup::prepareSearch(
         getCompletionListForComplexKeyword(preWord);
         break;
     case CodeCompletionType::Types:
-        mIncludedFiles = mParser->getFileIncludes(filename);
+        mIncludedFiles = mParser->getIncludedFiles(filename);
         getCompletionListForTypes(preWord,filename,line);
         break;
     case CodeCompletionType::FunctionWithoutDefinition:
-        mIncludedFiles = mParser->getFileIncludes(filename);
+        mIncludedFiles = mParser->getIncludedFiles(filename);
         getCompletionForFunctionWithoutDefinition(preWord, ownerExpression,memberOperator,memberExpression, filename,line);
         break;
     case CodeCompletionType::Namespaces:
-        mIncludedFiles = mParser->getFileIncludes(filename);
+        mIncludedFiles = mParser->getIncludedFiles(filename);
         getCompletionListForNamespaces(preWord,filename,line);
         break;
     case CodeCompletionType::KeywordsOnly:
@@ -114,7 +114,7 @@ void CodeCompletionPopup::prepareSearch(
         getKeywordCompletionFor(customKeywords);
         break;
     default:
-        mIncludedFiles = mParser->getFileIncludes(filename);
+        mIncludedFiles = mParser->getIncludedFiles(filename);
         getCompletionFor(ownerExpression,memberOperator,memberExpression, filename,line, customKeywords);
     }
     setCursor(oldCursor);