diff --git a/base/observer_list.hpp b/base/observer_list.hpp
index 915c78f1d8..6599afbe91 100644
--- a/base/observer_list.hpp
+++ b/base/observer_list.hpp
@@ -1,5 +1,7 @@
 #pragma once
 
+#include "../base/logging.hpp"
+
 #include "../std/algorithm.hpp"
 #include "../std/mutex.hpp"
 #include "../std/vector.hpp"
@@ -17,7 +19,10 @@ public:
     lock_guard<mutex> lock(m_observersLock);
     auto it = find(m_observers.begin(), m_observers.end(), &observer);
     if (it != m_observers.end())
+    {
+      LOG(LWARNING, ("Can't add the same observer twice:", &observer));
       return false;
+    }
     m_observers.push_back(&observer);
     return true;
   }
@@ -27,7 +32,10 @@ public:
     lock_guard<mutex> lock(m_observersLock);
     auto it = find(m_observers.begin(), m_observers.end(), &observer);
     if (it == m_observers.end())
+    {
+      LOG(LWARNING, ("Can't remove non-registered observer:", &observer));
       return false;
+    }
     m_observers.erase(it);
     return true;
   }
diff --git a/drape_head/drape_surface.cpp b/drape_head/drape_surface.cpp
index 8a41da185b..e1286e27cf 100644
--- a/drape_head/drape_surface.cpp
+++ b/drape_head/drape_surface.cpp
@@ -32,7 +32,8 @@ DrapeSurface::DrapeSurface()
   Platform & pl = GetPlatform();
   pl.GetFilesByExt(pl.WritableDir(), DATA_FILE_EXTENSION, maps);
 
-  for_each(maps.begin(), maps.end(), bind(&model::FeaturesFetcher::RegisterMap, &m_model, _1));
+  feature::DataHeader::Version version;
+  for_each(maps.begin(), maps.end(), bind(&model::FeaturesFetcher::RegisterMap, &m_model, _1, version));
   ///}
   ///
   m_navigator.LoadState();
diff --git a/generator/generator_tests/check_mwms.cpp b/generator/generator_tests/check_mwms.cpp
index 45a3f417e6..cc97cf4c21 100644
--- a/generator/generator_tests/check_mwms.cpp
+++ b/generator/generator_tests/check_mwms.cpp
@@ -2,6 +2,7 @@
 
 #include "../../map/feature_vec_model.hpp"
 
+#include "../../indexer/data_header.hpp"
 #include "../../indexer/interval_index.hpp"
 
 #include "../../platform/platform.hpp"
@@ -23,7 +24,8 @@ UNIT_TEST(CheckMWM_LoadAll)
   {
     try
     {
-      m.RegisterMap(s);
+      feature::DataHeader::Version version;
+      m.RegisterMap(s, version);
     }
     catch (RootException const & ex)
     {
diff --git a/generator/routing_generator.cpp b/generator/routing_generator.cpp
index 56e38e40ca..7e5648e634 100644
--- a/generator/routing_generator.cpp
+++ b/generator/routing_generator.cpp
@@ -9,10 +9,11 @@
 #include "../routing/osrm_router.hpp"
 #include "../routing/cross_routing_context.hpp"
 
-#include "../indexer/index.hpp"
 #include "../indexer/classificator_loader.hpp"
+#include "../indexer/data_header.hpp"
 #include "../indexer/feature.hpp"
 #include "../indexer/ftypes_matcher.hpp"
+#include "../indexer/index.hpp"
 #include "../indexer/mercator.hpp"
 
 #include "../geometry/distance_on_sphere.hpp"
@@ -226,7 +227,8 @@ void BuildRoutingIndex(string const & baseDir, string const & countryName, strin
   string const mwmFile = baseDir + countryName + DATA_FILE_EXTENSION;
   Index index;
   m2::RectD rect;
-  if (!index.Register(mwmFile, rect))
+  feature::DataHeader::Version version;
+  if (!index.Register(mwmFile, rect, version))
   {
     LOG(LCRITICAL, ("MWM file not found"));
     return;
diff --git a/indexer/index.cpp b/indexer/index.cpp
index b07c6375ec..724e0fede3 100644
--- a/indexer/index.cpp
+++ b/indexer/index.cpp
@@ -1,5 +1,4 @@
 #include "index.hpp"
-#include "data_header.hpp"
 
 #include "../platform/platform.hpp"
 
@@ -41,23 +40,23 @@ string Index::MwmLock::GetFileName() const
 // Index implementation
 //////////////////////////////////////////////////////////////////////////////////
 
-int Index::GetInfo(string const & name, MwmInfo & info) const
+bool Index::GetVersion(string const & name, MwmInfo & info,
+                       feature::DataHeader::Version & version) const
 {
   MwmValue value(name);
 
   feature::DataHeader const & h = value.GetHeader();
-  if (h.IsMWMSuitable())
-  {
-    info.m_limitRect = h.GetBounds();
+  if (!h.IsMWMSuitable())
+    return false;
 
-    pair<int, int> const scaleR = h.GetScaleRange();
-    info.m_minScale = static_cast<uint8_t>(scaleR.first);
-    info.m_maxScale = static_cast<uint8_t>(scaleR.second);
+  info.m_limitRect = h.GetBounds();
 
-    return h.GetVersion();
-  }
-  else
-    return -1;
+  pair<int, int> const scaleR = h.GetScaleRange();
+  info.m_minScale = static_cast<uint8_t>(scaleR.first);
+  info.m_maxScale = static_cast<uint8_t>(scaleR.second);
+
+  version = h.GetVersion();
+  return true;
 }
 
 MwmValue * Index::CreateValue(string const & name) const
@@ -105,28 +104,30 @@ namespace
   }
 }
 
-int Index::RegisterMap(string const & fileName, m2::RectD & rect)
+bool Index::RegisterMap(string const & fileName, m2::RectD & rect,
+                        feature::DataHeader::Version & version)
 {
   if (GetPlatform().IsFileExistsByFullPath(GetFullPath(fileName + READY_FILE_EXTENSION)))
   {
-    int const ret = UpdateMap(fileName, rect);
-    switch (ret)
+    UpdateStatus status = UpdateMap(fileName, rect, version);
+    switch (status)
     {
-    case -1:
-      return -1;
-    case -2:
-      // Not dangerous, but it's strange when adding existing maps.
-      ASSERT(false, ());
-      return feature::DataHeader::v3;
-    default:
-      return ret;
+      case UPDATE_STATUS_OK:
+        return true;
+      case UPDATE_STATUS_BAD_FILE:
+        return false;
+      case UPDATE_STATUS_UPDATE_DELAYED:
+        // Not dangerous, but it's strange when adding existing maps.
+        ASSERT(false, ());
+        version = feature::DataHeader::v3;
+        return true;
     }
   }
 
-  int rv = Register(fileName, rect);
-  if (rv >= 0)
-    m_observers.ForEach(&Observer::OnMapRegistered, fileName);
-  return rv;
+  if (!Register(fileName, rect, version))
+    return false;
+  m_observers.ForEach(&Observer::OnMapRegistered, fileName);
+  return true;
 }
 
 bool Index::DeleteMap(string const & fileName)
@@ -153,9 +154,10 @@ bool Index::RemoveObserver(Observer & observer)
   return m_observers.Remove(observer);
 }
 
-int Index::UpdateMap(string const & fileName, m2::RectD & rect)
+Index::UpdateStatus Index::UpdateMap(string const & fileName, m2::RectD & rect,
+                                     feature::DataHeader::Version & version)
 {
-  int rv = -1;
+  UpdateStatus status = UPDATE_STATUS_OK;
   {
     lock_guard<mutex> lock(m_lock);
 
@@ -163,17 +165,19 @@ int Index::UpdateMap(string const & fileName, m2::RectD & rect)
     if (id != INVALID_MWM_ID && m_info[id].m_lockCount > 0)
     {
       m_info[id].SetStatus(MwmInfo::STATUS_PENDING_UPDATE);
-      rv = -2;
-    } else {
+      status = UPDATE_STATUS_UPDATE_DELAYED;
+    }
+    else
+    {
       ReplaceFileWithReady(fileName);
-      rv = RegisterImpl(fileName, rect);
+      status = RegisterImpl(fileName, rect, version) ? UPDATE_STATUS_OK : UPDATE_STATUS_BAD_FILE;
     }
   }
-  if (rv != -1)
+  if (status != UPDATE_STATUS_BAD_FILE)
     m_observers.ForEach(&Observer::OnMapUpdateIsReady, fileName);
-  if (rv >= 0)
+  if (status == UPDATE_STATUS_OK)
     m_observers.ForEach(&Observer::OnMapUpdated, fileName);
-  return rv;
+  return status;
 }
 
 void Index::UpdateMwmInfo(MwmId id)
diff --git a/indexer/index.hpp b/indexer/index.hpp
index 1e1f97080d..aa21d9f714 100644
--- a/indexer/index.hpp
+++ b/indexer/index.hpp
@@ -30,16 +30,23 @@ public:
   string GetFileName() const;
 };
 
-
 class Index : public MwmSet
 {
 protected:
-  /// @return mwm format version or -1 if file isn't suitable (greater version).
-  virtual int GetInfo(string const & name, MwmInfo & info) const;
-  virtual MwmValue * CreateValue(string const & name) const;
-  virtual void UpdateMwmInfo(MwmId id);
+  // MwmSet overrides:
+  bool GetVersion(string const & name, MwmInfo & info,
+                  feature::DataHeader::Version & version) const override;
+  MwmValue * CreateValue(string const & name) const override;
+  void UpdateMwmInfo(MwmId id) override;
 
 public:
+  enum UpdateStatus
+  {
+    UPDATE_STATUS_OK,
+    UPDATE_STATUS_BAD_FILE,
+    UPDATE_STATUS_UPDATE_DELAYED
+  };
+
   /// An Observer interface to MwmSet. Note that these functions can
   /// be called from *ANY* thread because most signals are sent when
   /// some thread releases its MwmLock, so overrides must be as fast
@@ -84,17 +91,24 @@ public:
 
   /// Registers new map.
   ///
-  /// \return mwm format version or -1 if file isn't suitable (greater
-  /// version).
-  int RegisterMap(string const & fileName, m2::RectD & rect);
+  /// \return True if map was successfully registered. In this case
+  ///         version is set to the file format version. Otherwise
+  ///         returns false and version is not modified. This means
+  ///         that file isn't suitable, for example, because of
+  ///         greater version.
+  bool RegisterMap(string const & fileName, m2::RectD & rect,
+                   feature::DataHeader::Version & version);
 
   /// Replaces map file corresponding to fileName with a new one, when
   /// it's possible - no clients of the map file. Otherwise, update
   /// will be delayed.
   ///
-  /// \return mwm format version or -1 if file isn't suitable (greater
-  /// version).  -2 if file is busy now (delayed update).
-  int UpdateMap(string const & fileName, m2::RectD & rect);
+  /// \return UPDATE_STATUS_OK, when map file have updated, as a side effect
+  ///         sets version to an mwm format version.
+  ///         UPDATE_STATUS_BAD_FILE when file isn't suitable for update.
+  ///         UPDATE_STATUS_UPDATE_DELAYED when update is delayed.
+  UpdateStatus UpdateMap(string const & fileName, m2::RectD & rect,
+                         feature::DataHeader::Version & version);
 
   /// Deletes map both from file system and internal tables, also,
   /// deletes all files related to the map. If map was successfully
diff --git a/indexer/indexer_tests/index_test.cpp b/indexer/indexer_tests/index_test.cpp
index 8d09c4d653..7fbd85b4e1 100644
--- a/indexer/indexer_tests/index_test.cpp
+++ b/indexer/indexer_tests/index_test.cpp
@@ -1,4 +1,6 @@
 #include "../../testing/testing.hpp"
+
+#include "../data_header.hpp"
 #include "../index.hpp"
 
 #include "../../coding/file_name_utils.hpp"
@@ -75,7 +77,8 @@ UNIT_TEST(Index_Parse)
   Index index;
 
   m2::RectD dummyRect;
-  index.RegisterMap("minsk-pass" DATA_FILE_EXTENSION, dummyRect);
+  feature::DataHeader::Version dummyVersion;
+  index.RegisterMap("minsk-pass" DATA_FILE_EXTENSION, dummyRect, dummyVersion);
 
   // Make sure that index is actually parsed.
   NoopFunctor fn;
@@ -100,14 +103,15 @@ UNIT_TEST(Index_MwmStatusNotifications)
 
   TEST_EQUAL(0, observer.map_registered_calls(), ());
   m2::RectD dummyRect;
+  feature::DataHeader::Version dummyVersion;
 
   // Check that observers are triggered after map registration.
-  TEST_LESS_OR_EQUAL(0, index.RegisterMap(testMapName, dummyRect), ());
+  TEST(index.RegisterMap(testMapName, dummyRect, dummyVersion), ());
   TEST_EQUAL(1, observer.map_registered_calls(), ());
 
   // Check that map can't registered twice and observers aren't
   // triggered.
-  TEST_EQUAL(-1, index.RegisterMap(testMapName, dummyRect), ());
+  TEST(!index.RegisterMap(testMapName, dummyRect, dummyVersion), ());
   TEST_EQUAL(1, observer.map_registered_calls(), ());
 
   TEST(my::CopyFileX(testMapPath, testMapUpdatePath), ());
@@ -116,7 +120,7 @@ UNIT_TEST(Index_MwmStatusNotifications)
   // Check that observers are notified when map is deleted.
   TEST_EQUAL(0, observer.map_update_is_ready_calls(), ());
   TEST_EQUAL(0, observer.map_updated_calls(), ());
-  TEST_LESS_OR_EQUAL(0, index.UpdateMap(testMapName, dummyRect), ());
+  TEST_EQUAL(Index::UPDATE_STATUS_OK, index.UpdateMap(testMapName, dummyRect, dummyVersion), ());
   TEST_EQUAL(1, observer.map_update_is_ready_calls(), ());
   TEST_EQUAL(1, observer.map_updated_calls(), ());
 
diff --git a/indexer/indexer_tests/mwm_set_test.cpp b/indexer/indexer_tests/mwm_set_test.cpp
index 12eb87a7a3..6b1f15b520 100644
--- a/indexer/indexer_tests/mwm_set_test.cpp
+++ b/indexer/indexer_tests/mwm_set_test.cpp
@@ -11,12 +11,14 @@ namespace
   class TestMwmSet : public MwmSet
   {
   protected:
-    virtual int GetInfo(string const & path, MwmInfo & info) const
+    virtual bool GetVersion(string const & path, MwmInfo & info,
+                            feature::DataHeader::Version & version) const
     {
       int n = path[0] - '0';
       info.m_maxScale = n;
       info.m_limitRect = m2::RectD(0, 0, 1, 1);
-      return 1;
+      version = feature::DataHeader::lastVersion;
+      return true;
     }
     virtual MwmValue * CreateValue(string const &) const
     {
diff --git a/indexer/mwm_set.cpp b/indexer/mwm_set.cpp
index 46d9bea017..359640066d 100644
--- a/indexer/mwm_set.cpp
+++ b/indexer/mwm_set.cpp
@@ -102,7 +102,8 @@ MwmSet::MwmId MwmSet::GetIdByName(string const & name)
   return INVALID_MWM_ID;
 }
 
-int MwmSet::Register(string const & fileName, m2::RectD & rect)
+bool MwmSet::Register(string const & fileName, m2::RectD & rect,
+                      feature::DataHeader::Version & version)
 {
   lock_guard<mutex> lock(m_lock);
 
@@ -110,23 +111,23 @@ int MwmSet::Register(string const & fileName, m2::RectD & rect)
   if (id != INVALID_MWM_ID)
   {
     if (m_info[id].IsRegistered())
-      LOG(LWARNING, ("Trying to add already added map", fileName));
+      LOG(LWARNING, ("Trying to add already registered map", fileName));
     else
       m_info[id].SetStatus(MwmInfo::STATUS_UP_TO_DATE);
 
-    return -1;
+    return false;
   }
 
-  return RegisterImpl(fileName, rect);
+  return RegisterImpl(fileName, rect, version);
 }
 
-int MwmSet::RegisterImpl(string const & fileName, m2::RectD & rect)
+bool MwmSet::RegisterImpl(string const & fileName, m2::RectD & rect,
+                          feature::DataHeader::Version & version)
 {
   // this function can throw an exception for bad mwm file
   MwmInfo info;
-  int const version = GetInfo(fileName, info);
-  if (version == -1)
-    return -1;
+  if (!GetVersion(fileName, info, version))
+    return false;
 
   info.SetStatus(MwmInfo::STATUS_UP_TO_DATE);
 
@@ -135,8 +136,8 @@ int MwmSet::RegisterImpl(string const & fileName, m2::RectD & rect)
   m_info[id] = info;
 
   rect = info.m_limitRect;
-  ASSERT ( rect.IsValid(), () );
-  return version;
+  ASSERT(rect.IsValid(), ());
+  return true;
 }
 
 bool MwmSet::DeregisterImpl(MwmId id)
diff --git a/indexer/mwm_set.hpp b/indexer/mwm_set.hpp
index f179831c6b..6d045a6877 100644
--- a/indexer/mwm_set.hpp
+++ b/indexer/mwm_set.hpp
@@ -1,4 +1,7 @@
 #pragma once
+
+#include "data_header.hpp"
+
 #include "../geometry/rect2d.hpp"
 
 #include "../std/deque.hpp"
@@ -83,20 +86,25 @@ public:
   /// Registers new map in the set.
   /// @param[in]  fileName  File name (without full path) of country.
   /// @param[out] rect      Limit rect of country.
-  /// @return Map format version or -1 if not added (already exists).
+  /// @param[out] version   Version of the file.
+  ///
+  /// @return True when map is registered, false otherwise - map already
+  /// exists or it's not possible to get mwm's version.
   //@{
 protected:
-  int RegisterImpl(string const & fileName, m2::RectD & rect);
+  bool RegisterImpl(string const & fileName, m2::RectD & rect,
+                    feature::DataHeader::Version & version);
 
 public:
-  int Register(string const & fileName, m2::RectD & rect);
+  bool Register(string const & fileName, m2::RectD & rect, feature::DataHeader::Version & version);
   //@}
 
   /// Used in unit tests only.
   inline void Register(string const & fileName)
   {
-    m2::RectD dummy;
-    CHECK(Register(fileName, dummy), ());
+    m2::RectD dummyRect;
+    feature::DataHeader::Version dummyVersion;
+    CHECK(Register(fileName, dummyRect, dummyVersion), ());
   }
 
   /// @name Remove mwm.
@@ -126,8 +134,10 @@ public:
   void ClearCache();
 
 protected:
-  /// @return mwm format version
-  virtual int GetInfo(string const & name, MwmInfo & info) const = 0;
+  /// @return True when it's possible to get file format version - in
+  ///         this case version is set to the file format version.
+  virtual bool GetVersion(string const & name, MwmInfo & info,
+                          feature::DataHeader::Version & version) const = 0;
   virtual MwmValueBase * CreateValue(string const & name) const = 0;
 
   void Cleanup();
diff --git a/map/benchmark_engine.cpp b/map/benchmark_engine.cpp
index 511035d11f..94dd3b8296 100644
--- a/map/benchmark_engine.cpp
+++ b/map/benchmark_engine.cpp
@@ -1,6 +1,8 @@
 #include "benchmark_engine.hpp"
 #include "framework.hpp"
 
+#include "../indexer/data_header.hpp"
+
 #include "../platform/settings.hpp"
 #include "../platform/platform.hpp"
 
@@ -131,8 +133,9 @@ void BenchmarkEngine::PrepareMaps()
   // add only maps needed for benchmarks
   MapsCollector collector;
   ForEachBenchmarkRecord(collector);
+  feature::DataHeader::Version version;
   for_each(collector.m_maps.begin(), collector.m_maps.end(),
-           bind(&Framework::RegisterMap, m_framework, _1));
+           bind(&Framework::RegisterMap, m_framework, _1, version));
 }
 
 BenchmarkEngine::BenchmarkEngine(Framework * fw)
diff --git a/map/benchmark_tool/features_loading.cpp b/map/benchmark_tool/features_loading.cpp
index 0f56adcc04..efb6225336 100644
--- a/map/benchmark_tool/features_loading.cpp
+++ b/map/benchmark_tool/features_loading.cpp
@@ -3,6 +3,7 @@
 #include "../feature_vec_model.hpp"
 
 #include "../../indexer/data_factory.hpp"
+#include "../../indexer/data_header.hpp"
 #include "../../indexer/feature_visibility.hpp"
 #include "../../indexer/scales.hpp"
 
@@ -109,7 +110,8 @@ void RunFeaturesLoadingBenchmark(string const & file, pair<int, int> scaleR, All
     return;
 
   model::FeaturesFetcher src;
-  src.RegisterMap(file);
+  feature::DataHeader::Version version;
+  src.RegisterMap(file, version);
 
   RunBenchmark(src, header.GetBounds(), scaleR, res);
 }
diff --git a/map/feature_vec_model.cpp b/map/feature_vec_model.cpp
index 5acb0699a3..3ad91ec761 100644
--- a/map/feature_vec_model.cpp
+++ b/map/feature_vec_model.cpp
@@ -32,26 +32,25 @@ void FeaturesFetcher::InitClassificator()
   }
 }
 
-int FeaturesFetcher::RegisterMap(string const & file)
+bool FeaturesFetcher::RegisterMap(string const & file, feature::DataHeader::Version & version)
 {
-  int version = -1;
-
   try
   {
     m2::RectD r;
-    version = m_multiIndex.RegisterMap(file, r);
-
-    if (version != -1)
-      m_rect.Add(r);
-    else
-      LOG(LWARNING, ("Can't add map", file, "Probably it's already added or has newer data version."));
+    if (!m_multiIndex.RegisterMap(file, r, version))
+    {
+      LOG(LWARNING,
+          ("Can't add map", file, "Probably it's already added or has newer data version."));
+      return false;
+    }
+    m_rect.Add(r);
+    return true;
   }
   catch (RootException const & e)
   {
     LOG(LERROR, ("IO error while adding ", file, " map. ", e.what()));
+    return false;
   }
-
-  return version;
 }
 
 void FeaturesFetcher::DeregisterMap(string const & file) { m_multiIndex.Deregister(file); }
@@ -65,7 +64,8 @@ bool FeaturesFetcher::DeleteMap(string const & file)
 
 bool FeaturesFetcher::UpdateMap(string const & file, m2::RectD & rect)
 {
-  return m_multiIndex.UpdateMap(file, rect) >= 0;
+  feature::DataHeader::Version version;
+  return m_multiIndex.UpdateMap(file, rect, version);
 }
 
 //void FeaturesFetcher::Clean()
diff --git a/map/feature_vec_model.hpp b/map/feature_vec_model.hpp
index b786ced872..f0de9c28b3 100644
--- a/map/feature_vec_model.hpp
+++ b/map/feature_vec_model.hpp
@@ -1,5 +1,6 @@
 #pragma once
 
+#include "../indexer/data_header.hpp"
 #include "../indexer/index.hpp"
 
 #include "../geometry/rect2d.hpp"
@@ -30,9 +31,10 @@ namespace model
     void InitClassificator();
 
     /// @param[in] file Name of mwm file with extension.
-    //@{
-    /// @return MWM format version for file or -1 if error and map was not added
-    int RegisterMap(string const & file);
+    //{@
+    /// @return True when map was successfully registered, also, sets
+    ///         version to the file format version.
+    bool RegisterMap(string const & file, feature::DataHeader::Version & version);
 
     /// Deregisters map denoted by file from internal records.
     void DeregisterMap(string const & file);
diff --git a/map/framework.cpp b/map/framework.cpp
index 551b2730b1..446093381d 100644
--- a/map/framework.cpp
+++ b/map/framework.cpp
@@ -84,11 +84,13 @@ namespace
   static const int BM_TOUCH_PIXEL_INCREASE = 20;
 }
 
-int Framework::RegisterMap(string const & file)
+bool Framework::RegisterMap(string const & file, feature::DataHeader::Version & version)
 {
   LOG(LINFO, ("Loading map:", file));
 
-  int const version = m_model.RegisterMap(file);
+  if (!m_model.RegisterMap(file, version))
+    return false;
+
   if (version == feature::DataHeader::v1)
   {
     // Now we do force delete of old (April 2011) maps.
@@ -97,10 +99,11 @@ int Framework::RegisterMap(string const & file)
     DeregisterMap(file);
     VERIFY(my::DeleteFileX(GetPlatform().WritablePathForFile(file)), ());
 
-    return -1;
+    version = feature::DataHeader::unknownVersion;
+    return false;
   }
 
-  return version;
+  return true;
 }
 
 void Framework::DeregisterMap(string const & file) { m_model.DeregisterMap(file); }
@@ -408,9 +411,9 @@ void Framework::RegisterAllMaps()
   GetMaps(maps);
   for_each(maps.begin(), maps.end(), [&](string const & file)
   {
-    int const v = RegisterMap(file);
-    if (v != -1 && v < minVersion)
-      minVersion = v;
+    feature::DataHeader::Version version;
+    if (RegisterMap(file, version) && version < minVersion)
+      minVersion = version;
   });
 
   m_countryTree.Init(maps);
diff --git a/map/framework.hpp b/map/framework.hpp
index 503e82ef9f..15bd80a419 100644
--- a/map/framework.hpp
+++ b/map/framework.hpp
@@ -25,6 +25,8 @@
 #include "routing_session.hpp"
 #include "country_tree.hpp"
 
+#include "../indexer/data_header.hpp"
+
 #include "../search/search_engine.hpp"
 
 #include "../storage/storage.hpp"
@@ -170,8 +172,9 @@ public:
 
   /// Registers local map file in internal indexes.
   ///
-  /// @return Inner mwm data version from header or -1 in case of error.
-  int RegisterMap(string const & file);
+  /// @return True and inner mwm data version from header in version
+  ///         or false in case of errors.
+  bool RegisterMap(string const & file, feature::DataHeader::Version & version);
   //@}
 
   /// Deletes all disk files corresponding to country.
diff --git a/map/map_tests/bookmarks_test.cpp b/map/map_tests/bookmarks_test.cpp
index ee7cd28d8e..f20ec89f87 100644
--- a/map/map_tests/bookmarks_test.cpp
+++ b/map/map_tests/bookmarks_test.cpp
@@ -1,5 +1,7 @@
 #include "../../testing/testing.hpp"
 
+#include "../../indexer/data_header.hpp"
+
 #include "../../map/framework.hpp"
 
 #include "../../search/result.hpp"
@@ -398,7 +400,8 @@ UNIT_TEST(Bookmarks_AddressInfo)
   // Maps added in constructor (we need minsk-pass.mwm only)
   Framework fm;
   fm.DeregisterAllMaps();
-  fm.RegisterMap("minsk-pass.mwm");
+  feature::DataHeader::Version version;
+  fm.RegisterMap("minsk-pass.mwm", version);
 
   fm.OnSize(800, 600);
 
diff --git a/map/mwm_tests/multithread_mwm_test.cpp b/map/mwm_tests/multithread_mwm_test.cpp
index ea5b9706e5..83b387e4cd 100644
--- a/map/mwm_tests/multithread_mwm_test.cpp
+++ b/map/mwm_tests/multithread_mwm_test.cpp
@@ -62,7 +62,9 @@ namespace
   {
     SourceT src;
     src.InitClassificator();
-    src.RegisterMap(file + DATA_FILE_EXTENSION);
+
+    feature::DataHeader::Version version;
+    src.RegisterMap(file + DATA_FILE_EXTENSION, version);
 
     // Check that country rect is valid and not infinity.
     m2::RectD const r = src.GetWorldRect();
diff --git a/map/mwm_tests/mwm_foreach_test.cpp b/map/mwm_tests/mwm_foreach_test.cpp
index 15c2544299..a6ee0375e3 100644
--- a/map/mwm_tests/mwm_foreach_test.cpp
+++ b/map/mwm_tests/mwm_foreach_test.cpp
@@ -250,7 +250,9 @@ void RunTest(string const & file)
 {
   model::FeaturesFetcher src1;
   src1.InitClassificator();
-  src1.RegisterMap(file);
+
+  feature::DataHeader::Version version;
+  src1.RegisterMap(file, version);
 
   vector<m2::RectD> rects;
   rects.push_back(src1.GetWorldRect());
diff --git a/map/mwm_tests/mwm_index_test.cpp b/map/mwm_tests/mwm_index_test.cpp
index f162d4c39b..a0ad429bf0 100644
--- a/map/mwm_tests/mwm_index_test.cpp
+++ b/map/mwm_tests/mwm_index_test.cpp
@@ -39,7 +39,8 @@ public:
 bool RunTest(string const & fileName, int lowS, int highS)
 {
   model::FeaturesFetcher src;
-  if (src.RegisterMap(fileName) == -1)
+  feature::DataHeader::Version version;
+  if (!src.RegisterMap(fileName, version) || version == feature::DataHeader::unknownVersion)
     return false;
 
   CheckNonEmptyGeometry doCheck;
@@ -52,7 +53,6 @@ bool RunTest(string const & fileName, int lowS, int highS)
 
   return true;
 }
-
 }
 
 UNIT_TEST(ForEachFeatureID_Test)
diff --git a/search/search_tests/house_detector_tests.cpp b/search/search_tests/house_detector_tests.cpp
index 689a79d140..4a11789e68 100644
--- a/search/search_tests/house_detector_tests.cpp
+++ b/search/search_tests/house_detector_tests.cpp
@@ -8,10 +8,11 @@
 
 #include "../../geometry/distance_on_sphere.hpp"
 
-#include "../../indexer/ftypes_matcher.hpp"
-#include "../../indexer/scales.hpp"
-#include "../../indexer/index.hpp"
 #include "../../indexer/classificator_loader.hpp"
+#include "../../indexer/data_header.hpp"
+#include "../../indexer/ftypes_matcher.hpp"
+#include "../../indexer/index.hpp"
+#include "../../indexer/scales.hpp"
 
 #include "../../std/iostream.hpp"
 #include "../../std/fstream.hpp"
@@ -183,8 +184,8 @@ UNIT_TEST(HS_StreetsMerge)
 
   Index index;
   m2::RectD rect;
-
-  TEST(index.Register("minsk-pass.mwm", rect), ());
+  feature::DataHeader::Version version;
+  TEST(index.Register("minsk-pass.mwm", rect, version), ());
 
   {
     search::HouseDetector houser(&index);
@@ -272,7 +273,8 @@ UNIT_TEST(HS_FindHouseSmoke)
 
   Index index;
   m2::RectD rect;
-  index.Register("minsk-pass.mwm", rect);
+  feature::DataHeader::Version version;
+  index.Register("minsk-pass.mwm", rect, version);
 
   {
     vector<string> streetName(1, "Московская улица");
@@ -374,7 +376,8 @@ UNIT_TEST(HS_MWMSearch)
 
   Index index;
   m2::RectD rect;
-  if (!index.Register(country + ".mwm", rect))
+  feature::DataHeader::Version version;
+  if (!index.Register(country + ".mwm", rect, version))
   {
     LOG(LWARNING, ("MWM file not found"));
     return;
diff --git a/search/search_tests/locality_finder_test.cpp b/search/search_tests/locality_finder_test.cpp
index 10de3fd69e..dfd060e98e 100644
--- a/search/search_tests/locality_finder_test.cpp
+++ b/search/search_tests/locality_finder_test.cpp
@@ -1,6 +1,8 @@
 #include "../../testing/testing.hpp"
 
+#include "../../indexer/data_header.hpp"
 #include "../../indexer/index.hpp"
+
 #include "../locality_finder.hpp"
 
 namespace
@@ -33,7 +35,8 @@ UNIT_TEST(LocalityFinder)
 {
   Index index;
   m2::RectD rect;
-  TEST(index.Register("World.mwm", rect), ());
+  feature::DataHeader::Version version;
+  TEST(index.Register("World.mwm", rect, version), ());
 
   search::LocalityFinder finder(&index);
   finder.SetLanguage(StringUtf8Multilang::GetLangIndex("en"));