diff --git a/plugins/cmake/cmakeprojectdata.h b/plugins/cmake/cmakeprojectdata.h
--- a/plugins/cmake/cmakeprojectdata.h
+++ b/plugins/cmake/cmakeprojectdata.h
@@ -41,6 +41,12 @@
     KDevelop::Path::List frameworkDirectories;
     QString compileFlags;
     QHash<QString, QString> defines;
+
+    bool isEmpty() const
+    {
+        return includes.isEmpty() && frameworkDirectories.isEmpty()
+            && compileFlags.isEmpty() && defines.isEmpty();
+    }
 };
 inline QDebug &operator<<(QDebug debug, const CMakeFile& file)
 {
diff --git a/plugins/cmake/cmakeserverimportjob.cpp b/plugins/cmake/cmakeserverimportjob.cpp
--- a/plugins/cmake/cmakeserverimportjob.cpp
+++ b/plugins/cmake/cmakeserverimportjob.cpp
@@ -118,6 +118,13 @@
                     file.compileFlags = fileGroup.value(QStringLiteral("compileFlags")).toString();
                     file.defines = processDefines(file.compileFlags, fileGroup.value(QStringLiteral("defines")).toArray());
 
+                    // apparently some file groups do not contain build system information
+                    // skip these, as they would produce bogus results for us and break the fallback
+                    // implemented in CMakeManager::fileInformation
+                    if (file.isEmpty()) {
+                        continue;
+                    }
+
                     const auto sourcesArray = fileGroup.value(QStringLiteral("sources")).toArray();
                     const KDevelop::Path::List sources = kTransform<KDevelop::Path::List>(sourcesArray, [targetDir](const QJsonValue& val) { return KDevelop::Path(targetDir, val.toString()); });
                     targetSources.reserve(targetSources.size() + sources.size());