diff --git a/examples/openpose/openpose.cpp b/examples/openpose/openpose.cpp
index ec6304c3947e2e94ddb73706e8eb93f1d25ebc33..8cf7539d49ac286ae48ee37ba8a1932ecf8b0cb7 100755
--- a/examples/openpose/openpose.cpp
+++ b/examples/openpose/openpose.cpp
@@ -19,7 +19,12 @@
 #include <chrono> // `std::chrono::` functions and classes, e.g. std::chrono::milliseconds
 #include <thread> // std::this_thread
 // Other 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/headers.hpp>
diff --git a/examples/openpose/openposeBasicDemo.cpp b/examples/openpose/openposeBasicDemo.cpp
index bbe6a010a2e72a08ba89c3884284a400a02277c8..9868b18b10f2593e60360e67169c9d9b22777f6c 100644
--- a/examples/openpose/openposeBasicDemo.cpp
+++ b/examples/openpose/openposeBasicDemo.cpp
@@ -3,7 +3,12 @@
 #include <chrono> // `std::chrono::` functions and classes, e.g. std::chrono::milliseconds
 #include <thread> // std::this_thread
 // Other 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 
 // OpenPose dependencies
diff --git a/examples/tests/handFromJsonTest.cpp b/examples/tests/handFromJsonTest.cpp
index b24590c73ab1e8e8c5738be0ac281c59b9725772..1595e577802de9a8f706f8569c408f5d1e0df20d 100644
--- a/examples/tests/handFromJsonTest.cpp
+++ b/examples/tests/handFromJsonTest.cpp
@@ -2,7 +2,12 @@
 // Example to test hands accuracy given ground-truth bounding boxes.
 
 #include <chrono> // `std::chrono::` functions and classes, e.g. std::chrono::milliseconds
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 #include <openpose/headers.hpp>
 #include "wrapperHandFromJsonTest.hpp"
diff --git a/examples/tutorial_pose/1_extract_from_image.cpp b/examples/tutorial_pose/1_extract_from_image.cpp
index 15313190de5b8ec366f691f2a3dbe6b3f6113fa9..2d0959d5c901a15910e206197eee4afcf09d08c0 100644
--- a/examples/tutorial_pose/1_extract_from_image.cpp
+++ b/examples/tutorial_pose/1_extract_from_image.cpp
@@ -9,7 +9,12 @@
     // 2. `utilities` module: for the error & logging functions, i.e. op::error & op::log respectively
 
 // 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/core/headers.hpp>
diff --git a/examples/tutorial_pose/2_extract_pose_or_heatmat_from_image.cpp b/examples/tutorial_pose/2_extract_pose_or_heatmat_from_image.cpp
index d9d9e6e2a906544f2fca23e9084229f1f7ee2c3e..4b0a5a06a56c70b7fffc1931a1369add29169d0b 100644
--- a/examples/tutorial_pose/2_extract_pose_or_heatmat_from_image.cpp
+++ b/examples/tutorial_pose/2_extract_pose_or_heatmat_from_image.cpp
@@ -9,7 +9,12 @@
     // 2. `utilities` module: for the error & logging functions, i.e. op::error & op::log respectively
 
 // 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/core/headers.hpp>
diff --git a/examples/tutorial_thread/1_openpose_read_and_display.cpp b/examples/tutorial_thread/1_openpose_read_and_display.cpp
index 676c0fcbccad31dac01e67ebf4f22990988f4ef6..0ad74c6559f3037d5bf73061d165ed4812f47a87 100644
--- a/examples/tutorial_thread/1_openpose_read_and_display.cpp
+++ b/examples/tutorial_thread/1_openpose_read_and_display.cpp
@@ -8,7 +8,12 @@
     // 2. `utilities` module: for the error & logging functions, i.e. op::error & op::log respectively
 
 // 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/core/headers.hpp>
diff --git a/examples/tutorial_thread/2_user_processing_function.cpp b/examples/tutorial_thread/2_user_processing_function.cpp
index 24bf858890a12cc7084027fd5b3809c975f3e9ea..d6a3f0f39fd988769e2e602ad4054b221f929f9d 100644
--- a/examples/tutorial_thread/2_user_processing_function.cpp
+++ b/examples/tutorial_thread/2_user_processing_function.cpp
@@ -9,7 +9,12 @@
     // 2. `utilities` module: for the error & logging functions, i.e. op::error & op::log respectively
 
 // 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/core/headers.hpp>
diff --git a/examples/tutorial_thread/3_user_input_processing_and_output.cpp b/examples/tutorial_thread/3_user_input_processing_and_output.cpp
index e8b691534fb318f2aba90cac97c1fc123fe76cd8..4df67d8fb66cb5a18c4f2a1b2777f5bdb373725a 100644
--- a/examples/tutorial_thread/3_user_input_processing_and_output.cpp
+++ b/examples/tutorial_thread/3_user_input_processing_and_output.cpp
@@ -9,7 +9,12 @@
     // 2. `utilities` module: for the error & logging functions, i.e. op::error & op::log respectively
 
 // 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 // Option a) Importing all modules
diff --git a/examples/tutorial_thread/4_user_input_processing_output_and_datum.cpp b/examples/tutorial_thread/4_user_input_processing_output_and_datum.cpp
index 6659c8dd9bfbfe702fdd73c8a7391ec27fd09db4..a55f4c10d6d7ebc71def51fbf175567b23cdbc19 100644
--- a/examples/tutorial_thread/4_user_input_processing_output_and_datum.cpp
+++ b/examples/tutorial_thread/4_user_input_processing_output_and_datum.cpp
@@ -9,7 +9,12 @@
     // 2. `utilities` module: for the error & logging functions, i.e. op::error & op::log respectively
 
 // 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 // Option a) Importing all modules
diff --git a/examples/tutorial_wrapper/1_user_asynchronous_output.cpp b/examples/tutorial_wrapper/1_user_asynchronous_output.cpp
index 9b1dda9e1fa07f289d59d0429992081eac1b8048..c86058a91c9927226d1fb0726640da61de818072 100644
--- a/examples/tutorial_wrapper/1_user_asynchronous_output.cpp
+++ b/examples/tutorial_wrapper/1_user_asynchronous_output.cpp
@@ -19,7 +19,12 @@
 #include <chrono> // `std::chrono::` functions and classes, e.g. std::chrono::milliseconds
 #include <thread> // std::this_thread
 // Other 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/headers.hpp>
diff --git a/examples/tutorial_wrapper/2_user_synchronous.cpp b/examples/tutorial_wrapper/2_user_synchronous.cpp
index 78af7c9f29e939593bef172522093e4fe87caf76..da9413591aea143051e85a95ddf680f493082553 100644
--- a/examples/tutorial_wrapper/2_user_synchronous.cpp
+++ b/examples/tutorial_wrapper/2_user_synchronous.cpp
@@ -19,7 +19,12 @@
 #include <chrono> // `std::chrono::` functions and classes, e.g. std::chrono::milliseconds
 #include <thread> // std::this_thread
 // Other 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/headers.hpp>
diff --git a/examples/tutorial_wrapper/3_user_asynchronous.cpp b/examples/tutorial_wrapper/3_user_asynchronous.cpp
index 4d862964d190e7236940401e8e4d7815d193ade3..d51cb9d23d84d4823a9cf49de9237ecc5b1c4901 100644
--- a/examples/tutorial_wrapper/3_user_asynchronous.cpp
+++ b/examples/tutorial_wrapper/3_user_asynchronous.cpp
@@ -19,7 +19,12 @@
 #include <chrono> // `std::chrono::` functions and classes, e.g. std::chrono::milliseconds
 #include <thread> // std::this_thread
 // Other 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 // OpenPose dependencies
 #include <openpose/headers.hpp>
diff --git a/examples_beta/openpose3d/openpose3d.cpp b/examples_beta/openpose3d/openpose3d.cpp
index 535fc2268367f1e049a4b133a263bbf5083dc13d..7f5567fe570ab5648328d221f27bd23bc76d7f1f 100644
--- a/examples_beta/openpose3d/openpose3d.cpp
+++ b/examples_beta/openpose3d/openpose3d.cpp
@@ -19,7 +19,12 @@
 #include <thread> // std::this_thread
 #include <vector>
 // Other 3rdparty dependencies
-#include <gflags/gflags.h> // DEFINE_bool, DEFINE_int32, DEFINE_int64, DEFINE_uint64, DEFINE_double, DEFINE_string
+// GFlags: DEFINE_bool, _int32, _int64, _uint64, _double, _string
+#include <gflags/gflags.h>
+// Allow Google Flags in Ubuntu 14
+#ifndef GFLAGS_GFLAGS_H_
+    namespace gflags = google;
+#endif
 #include <glog/logging.h> // google::InitGoogleLogging
 
 // OpenPose dependencies
diff --git a/include/openpose/utilities/fileSystem.hpp b/include/openpose/utilities/fileSystem.hpp
index 2a585f320854945874f24f2d9e80855f1bc8c7d1..3e8cf4cde58aae9778ee7c7474706ff118f9d145 100644
--- a/include/openpose/utilities/fileSystem.hpp
+++ b/include/openpose/utilities/fileSystem.hpp
@@ -7,7 +7,9 @@ namespace op
 {
     OP_API void mkdir(const std::string& directoryPath);
 
-    OP_API bool exist(const std::string& directoryPath);
+    OP_API bool existDir(const std::string& directoryPath);
+
+    OP_API bool existFile(const std::string& filePath);
 
     OP_API bool isDirectory(const std::string& directoryPath);
 
diff --git a/src/openpose/core/netCaffe.cpp b/src/openpose/core/netCaffe.cpp
index ac8c99818f71c6e2b2b96ff47c805c71d1272091..f6cdb11722d2970f4da4dba0ec710e6e1f4a26f0 100644
--- a/src/openpose/core/netCaffe.cpp
+++ b/src/openpose/core/netCaffe.cpp
@@ -3,6 +3,7 @@
     #include <caffe/net.hpp>
 #endif
 #include <openpose/utilities/cuda.hpp>
+#include <openpose/utilities/fileSystem.hpp>
 #include <openpose/core/netCaffe.hpp>
 
 namespace op
@@ -32,6 +33,14 @@ namespace op
                 mCaffeTrainedModel{caffeTrainedModel},
                 mLastBlobName{lastBlobName}
             {
+                const std::string message{".\nPossible causes:\n\t1. Not downloading the OpenPose trained models."
+                                          "\n\t2. Not running OpenPose from the same directory where the `model`"
+                                          " folder is located.\n\t3. Using paths with spaces."};
+                if (!existFile(mCaffeProto))
+                    error("Prototxt file not found: " + mCaffeProto + message, __LINE__, __FUNCTION__, __FILE__);
+                if (!existFile(mCaffeTrainedModel))
+                    error("Caffe trained model file not found: " + mCaffeTrainedModel + message,
+                          __LINE__, __FUNCTION__, __FILE__);
             }
         #endif
     };
diff --git a/src/openpose/utilities/fileSystem.cpp b/src/openpose/utilities/fileSystem.cpp
index 67a02ba34b3b321c2e5797307f2dbe97e5837600..d1f62a49bdafbd0e791f8f81bbb5d58b909bc76f 100644
--- a/src/openpose/utilities/fileSystem.cpp
+++ b/src/openpose/utilities/fileSystem.cpp
@@ -1,7 +1,8 @@
+#include <cstdio> // fopen
 #include <boost/filesystem.hpp>
 #include <boost/range/iterator_range_core.hpp>
-#include <openpose/utilities/fileSystem.hpp>
 #include <openpose/utilities/string.hpp>
+#include <openpose/utilities/fileSystem.hpp>
 
 namespace op
 {
@@ -23,10 +24,11 @@ namespace op
         }
     }
 
-    bool exist(const std::string& directoryPath)
+    bool existDir(const std::string& directoryPath)
     {
         try
         {
+            // Maybe existFile also works for directories in Ubuntu/Windows/Mac?
             return boost::filesystem::exists(directoryPath);
         }
         catch (const std::exception& e)
@@ -36,6 +38,25 @@ namespace op
         }
     }
 
+    bool existFile(const std::string& filePath)
+    {
+        try
+        {
+            if (auto* file = fopen(filePath.c_str(), "r"))
+            {
+                fclose(file);
+                return true;
+            }
+            else
+                return false;
+        }
+        catch (const std::exception& e)
+        {
+            error(e.what(), __LINE__, __FUNCTION__, __FILE__);
+            return false;
+        }
+    }
+
     bool isDirectory(const std::string& directoryPath)
     {
         try
@@ -153,7 +174,7 @@ namespace op
         try
         {
             // Check folder exits
-            if (!exist(directoryPath))
+            if (!existDir(directoryPath))
                 error("Folder " + directoryPath + " does not exist.", __LINE__, __FUNCTION__, __FILE__);
             // Read images
             std::vector<std::string> filePaths;