diff --git a/src/libs/clangsupport/precompiledheadersupdatedmessage.h b/src/libs/clangsupport/precompiledheadersupdatedmessage.h
index 5a21b995df2..9c17a3c9da2 100644
--- a/src/libs/clangsupport/precompiledheadersupdatedmessage.h
+++ b/src/libs/clangsupport/precompiledheadersupdatedmessage.h
@@ -33,7 +33,11 @@ class PrecompiledHeadersUpdatedMessage
 {
 public:
     PrecompiledHeadersUpdatedMessage() = default;
-    PrecompiledHeadersUpdatedMessage(std::vector<ProjectPartPch> &&projectPartPchs)
+    PrecompiledHeadersUpdatedMessage(ProjectPartPch projectPartPch)
+    {
+        projectPartPchs.push_back(projectPartPch);
+    }
+    PrecompiledHeadersUpdatedMessage(ProjectPartPchs &&projectPartPchs)
         : projectPartPchs(std::move(projectPartPchs))
     {}
 
@@ -68,7 +72,7 @@ public:
     }
 
 public:
-    std::vector<ProjectPartPch> projectPartPchs;
+    ProjectPartPchs projectPartPchs;
 };
 
 CLANGSUPPORT_EXPORT QDebug operator<<(QDebug debug, const PrecompiledHeadersUpdatedMessage &message);
diff --git a/src/tools/clangpchmanagerbackend/source/pchcreator.cpp b/src/tools/clangpchmanagerbackend/source/pchcreator.cpp
index 3f858b50ee3..9b8683bcac5 100644
--- a/src/tools/clangpchmanagerbackend/source/pchcreator.cpp
+++ b/src/tools/clangpchmanagerbackend/source/pchcreator.cpp
@@ -111,6 +111,8 @@ Utils::SmallStringVector PchCreator::generateClangCompilerArguments(const PchTas
 
 void PchCreator::generatePch(PchTask &&pchTask)
 {
+    m_projectPartPch.projectPartId = pchTask.projectPartId();
+
     m_projectPartPch.lastModified = QDateTime::currentSecsSinceEpoch();
     auto content = generatePchIncludeFileContent(pchTask.includes);
     auto pchOutputPath = generatePchFilePath();
@@ -121,8 +123,6 @@ void PchCreator::generatePch(PchTask &&pchTask)
     m_clangTool.addFile(std::move(headerFilePath), content.clone(), std::move(commandLine));
     bool success = generatePch(NativeFilePath{headerFilePath}, content);
 
-    m_projectPartPch.projectPartId = pchTask.projectPartId();
-
     if (success) {
         m_sources = pchTask.sources;
         m_projectPartPch.pchPath = std::move(pchOutputPath);
@@ -168,17 +168,19 @@ void PchCreator::clear()
 
 void PchCreator::doInMainThreadAfterFinished()
 {
-    FilePathIds existingSources;
-    existingSources.reserve(m_sources.size());
-    std::set_difference(m_sources.begin(),
-                        m_sources.end(),
-                        m_generatedFilePathIds.begin(),
-                        m_generatedFilePathIds.end(),
-                        std::back_inserter(existingSources));
-    m_buildDependenciesStorage.updatePchCreationTimeStamp(m_projectPartPch.lastModified,
-                                                          m_projectPartPch.projectPartId);
-    m_clangPathwatcher.updateIdPaths({{m_projectPartPch.projectPartId, existingSources}});
-    m_pchManagerClient.precompiledHeadersUpdated(ProjectPartPchs{m_projectPartPch});
+    if (m_projectPartPch.projectPartId.isValid()) {
+        FilePathIds existingSources;
+        existingSources.reserve(m_sources.size());
+        std::set_difference(m_sources.begin(),
+                            m_sources.end(),
+                            m_generatedFilePathIds.begin(),
+                            m_generatedFilePathIds.end(),
+                            std::back_inserter(existingSources));
+        m_buildDependenciesStorage.updatePchCreationTimeStamp(m_projectPartPch.lastModified,
+                                                              m_projectPartPch.projectPartId);
+        m_clangPathwatcher.updateIdPaths({{m_projectPartPch.projectPartId, existingSources}});
+        m_pchManagerClient.precompiledHeadersUpdated({m_projectPartPch});
+    }
 }
 
 const FilePathCaching &PchCreator::filePathCache()
diff --git a/src/tools/clangpchmanagerbackend/source/pchtaskqueue.cpp b/src/tools/clangpchmanagerbackend/source/pchtaskqueue.cpp
index 1bf21712fd8..d2507ee8641 100644
--- a/src/tools/clangpchmanagerbackend/source/pchtaskqueue.cpp
+++ b/src/tools/clangpchmanagerbackend/source/pchtaskqueue.cpp
@@ -144,15 +144,19 @@ std::vector<PchTaskQueue::Task> PchTaskQueue::createProjectTasks(PchTasks &&pchT
     auto convert = [this](auto &&pchTask) {
         return [pchTask = std::move(pchTask), this](PchCreatorInterface &pchCreator) mutable {
             const auto projectPartId = pchTask.projectPartId();
-            pchTask.systemPchPath = m_precompiledHeaderStorage.fetchSystemPrecompiledHeaderPath(
-                projectPartId);
-            pchCreator.generatePch(std::move(pchTask));
-            const auto &projectPartPch = pchCreator.projectPartPch();
-            if (projectPartPch.pchPath.empty()) {
-                m_precompiledHeaderStorage.deleteProjectPrecompiledHeader(projectPartId);
+            if (pchTask.includes.size()) {
+                pchTask.systemPchPath = m_precompiledHeaderStorage.fetchSystemPrecompiledHeaderPath(
+                    projectPartId);
+                pchCreator.generatePch(std::move(pchTask));
+                const auto &projectPartPch = pchCreator.projectPartPch();
+                if (projectPartPch.pchPath.empty()) {
+                    m_precompiledHeaderStorage.deleteProjectPrecompiledHeader(projectPartId);
+                } else {
+                    m_precompiledHeaderStorage.insertProjectPrecompiledHeader(
+                        projectPartId, projectPartPch.pchPath, projectPartPch.lastModified);
+                }
             } else {
-                m_precompiledHeaderStorage.insertProjectPrecompiledHeader(
-                    projectPartId, projectPartPch.pchPath, projectPartPch.lastModified);
+                m_precompiledHeaderStorage.deleteProjectPrecompiledHeader(projectPartId);
             }
         };
     };
@@ -173,14 +177,17 @@ std::vector<PchTaskQueue::Task> PchTaskQueue::createSystemTasks(PchTasks &&pchTa
     auto convert = [this](auto &&pchTask) {
         return [pchTask = std::move(pchTask), this](PchCreatorInterface &pchCreator) mutable {
             const auto projectPartIds = pchTask.projectPartIds;
-            pchCreator.generatePch(std::move(pchTask));
-            const auto &projectPartPch = pchCreator.projectPartPch();
-            if (projectPartPch.pchPath.empty()) {
-                m_precompiledHeaderStorage.deleteSystemPrecompiledHeaders(projectPartIds);
+            if (pchTask.includes.size()) {
+                pchCreator.generatePch(std::move(pchTask));
+                const auto &projectPartPch = pchCreator.projectPartPch();
+                if (projectPartPch.pchPath.empty()) {
+                    m_precompiledHeaderStorage.deleteSystemPrecompiledHeaders(projectPartIds);
+                } else {
+                    m_precompiledHeaderStorage.insertSystemPrecompiledHeaders(
+                        projectPartIds, projectPartPch.pchPath, projectPartPch.lastModified);
+                }
             } else {
-                m_precompiledHeaderStorage.insertSystemPrecompiledHeaders(projectPartIds,
-                                                                          projectPartPch.pchPath,
-                                                                          projectPartPch.lastModified);
+                m_precompiledHeaderStorage.deleteSystemPrecompiledHeaders(projectPartIds);
             }
         };
     };
diff --git a/tests/unit/unittest/pchcreator-test.cpp b/tests/unit/unittest/pchcreator-test.cpp
index 5e16948387c..9c40b7fea76 100644
--- a/tests/unit/unittest/pchcreator-test.cpp
+++ b/tests/unit/unittest/pchcreator-test.cpp
@@ -243,6 +243,15 @@ TEST_F(PchCreatorVerySlowTest, PchCreationTimeStampsAreUpdated)
     creator.doInMainThreadAfterFinished();
 }
 
+TEST_F(PchCreator, DoNothingInTheMainThreadIfGenerateWasNotCalled)
+{
+    EXPECT_CALL(mockBuildDependenciesStorage, updatePchCreationTimeStamp(_, _)).Times(0);
+    EXPECT_CALL(mockClangPathWatcher, updateIdPaths(_)).Times(0);
+    EXPECT_CALL(mockPchManagerClient, precompiledHeadersUpdated(_)).Times(0);
+
+    creator.doInMainThreadAfterFinished();
+}
+
 TEST_F(PchCreatorVerySlowTest, ProjectPartPchForCreatesPchForPchTask)
 {
     creator.generatePch(std::move(pchTask1));
diff --git a/tests/unit/unittest/pchtaskqueue-test.cpp b/tests/unit/unittest/pchtaskqueue-test.cpp
index 3e0bba1bc89..4a8c0862eef 100644
--- a/tests/unit/unittest/pchtaskqueue-test.cpp
+++ b/tests/unit/unittest/pchtaskqueue-test.cpp
@@ -326,6 +326,22 @@ TEST_F(PchTaskQueue, DeleteProjectPchEntryInDatabaseIfNoPchIsGenerated)
     tasks.front()(mockPchCreator);
 }
 
+TEST_F(PchTaskQueue, DeleteProjectPchEntryInDatabaseIfTasksHasNoIncludes)
+{
+    InSequence s;
+    MockPchCreator mockPchCreator;
+    ClangBackEnd::ProjectPartPch projectPartPch{{}, "", 0};
+    projectTask1.includes = {};
+    auto tasks = queue.createProjectTasks({projectTask1});
+
+    EXPECT_CALL(mockPrecompiledHeaderStorage, fetchSystemPrecompiledHeaderPath(_)).Times(0);
+    EXPECT_CALL(mockPchCreator, generatePch(_)).Times(0);
+    EXPECT_CALL(mockPchCreator, projectPartPch()).Times(0);
+    EXPECT_CALL(mockPrecompiledHeaderStorage, deleteProjectPrecompiledHeader(Eq(1)));
+
+    tasks.front()(mockPchCreator);
+}
+
 TEST_F(PchTaskQueue, CreateSystemTasksSizeEqualsInputSize)
 {
     auto tasks = queue.createSystemTasks({systemTask1, systemTask2});
@@ -362,4 +378,20 @@ TEST_F(PchTaskQueue, DeleteSystemPchEntryInDatabaseIfNoPchIsGenerated)
 
     tasks.front()(mockPchCreator);
 }
+
+TEST_F(PchTaskQueue, DeleteSystemPchEntryInDatabaseIfTasksHasNoIncludes)
+{
+    InSequence s;
+    MockPchCreator mockPchCreator;
+    ClangBackEnd::ProjectPartPch projectPartPch{{}, "", 0};
+    systemTask4.includes = {};
+    auto tasks = queue.createSystemTasks({systemTask4});
+
+    EXPECT_CALL(mockPchCreator, generatePch(_)).Times(0);
+    EXPECT_CALL(mockPchCreator, projectPartPch()).Times(0);
+    EXPECT_CALL(mockPrecompiledHeaderStorage,
+                deleteSystemPrecompiledHeaders(UnorderedElementsAre(1, 3)));
+
+    tasks.front()(mockPchCreator);
+}
 } // namespace