diff --git a/src/content/ContentReport.cpp b/src/content/ContentReport.cpp
index 54b4098d..1e524309 100644
--- a/src/content/ContentReport.cpp
+++ b/src/content/ContentReport.cpp
@@ -14,10 +14,12 @@
 ContentReport::ContentReport(
     const ContentIndices* indices, 
     size_t blocksCount, 
-    size_t itemsCount
+    size_t itemsCount,
+    uint regionsVersion
 )
     : blocks(blocksCount, indices->blocks, BLOCK_VOID, ContentType::BLOCK),
-      items(itemsCount, indices->items, ITEM_VOID, ContentType::ITEM)
+      items(itemsCount, indices->items, ITEM_VOID, ContentType::ITEM),
+      regionsVersion(regionsVersion)
 {}
 
 template <class T>
@@ -38,6 +40,8 @@ std::shared_ptr<ContentReport> ContentReport::create(
     }
 
     auto root = files::read_json(filename);
+    // TODO: remove default value 2 in 0.24
+    uint regionsVersion = root->get("region-version", 2U);
     auto blocklist = root->list("blocks");
     auto itemlist = root->list("items");
 
@@ -45,7 +49,8 @@ std::shared_ptr<ContentReport> ContentReport::create(
     size_t blocks_c = get_entries_count(indices->blocks, blocklist);
     size_t items_c = get_entries_count(indices->items, itemlist);
 
-    auto report = std::make_shared<ContentReport>(indices, blocks_c, items_c);
+    auto report = std::make_shared<ContentReport>(
+        indices, blocks_c, items_c, regionsVersion);
     report->blocks.setup(blocklist.get(), content->blocks);
     report->items.setup(itemlist.get(), content->items);
     report->buildIssues();
diff --git a/src/content/ContentReport.hpp b/src/content/ContentReport.hpp
index d4c1a056..416be01e 100644
--- a/src/content/ContentReport.hpp
+++ b/src/content/ContentReport.hpp
@@ -9,17 +9,22 @@
 #include "data/dynamic.hpp"
 #include "typedefs.hpp"
 #include "Content.hpp"
+#include "files/world_regions_fwd.hpp"
 
 namespace fs = std::filesystem;
 
 enum class ContentIssueType {
     REORDER,
     MISSING,
+    REGION_FORMAT_UPDATE,
 };
 
 struct ContentIssue {
     ContentIssueType issueType;
-    ContentType contentType;
+    union {
+        ContentType contentType;
+        RegionLayerIndex regionLayer;
+    };
 };
 
 struct ContentEntry {
@@ -29,12 +34,16 @@ struct ContentEntry {
 
 class WorldFiles;
 
+/// @brief Content unit lookup table
+/// @tparam T index type
+/// @tparam U unit class
 template <typename T, class U>
 class ContentUnitLUT {
     std::vector<T> indices;
     std::vector<std::string> names;
     bool missingContent = false;
     bool reorderContent = false;
+    /// @brief index that will be used to mark missing unit
     T missingValue;
     ContentType type;
 public:
@@ -110,13 +119,15 @@ class ContentReport {
 public:
     ContentUnitLUT<blockid_t, Block> blocks;
     ContentUnitLUT<itemid_t, ItemDef> items;
+    uint regionsVersion;
 
     std::vector<ContentIssue> issues;
 
     ContentReport(
         const ContentIndices* indices, 
         size_t blocks, 
-        size_t items
+        size_t items,
+        uint regionsVersion
     );
 
     static std::shared_ptr<ContentReport> create(
@@ -131,6 +142,9 @@ public:
     inline bool hasMissingContent() const {
         return blocks.hasMissingContent() || items.hasMissingContent();
     }
+    inline bool isUpgradeRequired() const {
+        return regionsVersion < REGION_FORMAT_VERSION;
+    }
     void buildIssues();
 
     const std::vector<ContentIssue>& getIssues() const;
diff --git a/src/files/WorldConverter.cpp b/src/files/WorldConverter.cpp
index c94708dd..a6b977bb 100644
--- a/src/files/WorldConverter.cpp
+++ b/src/files/WorldConverter.cpp
@@ -12,43 +12,111 @@
 #include "objects/Player.hpp"
 #include "util/ThreadPool.hpp"
 #include "voxels/Chunk.hpp"
+#include "items/Inventory.hpp"
 #include "WorldFiles.hpp"
 
 namespace fs = std::filesystem;
 
 static debug::Logger logger("world-converter");
 
-class ConverterWorker : public util::Worker<convert_task, int> {
+class ConverterWorker : public util::Worker<ConvertTask, int> {
     std::shared_ptr<WorldConverter> converter;
 public:
     ConverterWorker(std::shared_ptr<WorldConverter> converter)
         : converter(std::move(converter)) {
     }
 
-    int operator()(const std::shared_ptr<convert_task>& task) override {
+    int operator()(const std::shared_ptr<ConvertTask>& task) override {
         converter->convert(*task);
         return 0;
     }
 };
 
+void WorldConverter::addRegionsTasks(
+    RegionLayerIndex layerid,
+    ConvertTaskType taskType
+) {
+    const auto& regions = wfile->getRegions();
+    auto regionsFolder = regions.getRegionsFolder(layerid);
+    if (!fs::is_directory(regionsFolder)) {
+        return;
+    }
+    for (const auto& file : fs::directory_iterator(regionsFolder)) {
+        int x, z;
+        std::string name = file.path().stem().string();
+        if (!WorldRegions::parseRegionFilename(name, x, z)) {
+            logger.error() << "could not parse region name " << name;
+            continue;
+        }
+        tasks.push(ConvertTask {taskType, file.path(), x, z});
+    }
+}
+
+void WorldConverter::createUpgradeTasks() {
+    const auto& regions = wfile->getRegions();
+    for (auto& issue : report->getIssues()) {
+        if (issue.issueType != ContentIssueType::REGION_FORMAT_UPDATE) {
+            continue;
+        }
+        if (issue.regionLayer == REGION_LAYER_VOXELS) {
+            addRegionsTasks(issue.regionLayer, ConvertTaskType::UPGRADE_VOXELS);
+        } else {
+            addRegionsTasks(issue.regionLayer, ConvertTaskType::UPGRADE_SIMPLE);
+        }
+    }
+}
+
+void WorldConverter::createConvertTasks() {
+    auto handleReorder = [=](ContentType contentType) {
+        switch (contentType) {
+            case ContentType::BLOCK:
+                addRegionsTasks(
+                    REGION_LAYER_VOXELS,
+                    ConvertTaskType::VOXELS
+                );
+                break;
+            case ContentType::ITEM:
+                addRegionsTasks(
+                    REGION_LAYER_INVENTORIES,
+                    ConvertTaskType::INVENTORIES
+                );
+                break;
+            default:
+                break;
+        }
+    };
+
+    const auto& regions = wfile->getRegions();
+    for (auto& issue : report->getIssues()) {
+        switch (issue.issueType) {
+            case ContentIssueType::REGION_FORMAT_UPDATE:
+                break;
+            case ContentIssueType::MISSING:
+                throw std::runtime_error("issue can't be resolved");
+            case ContentIssueType::REORDER:
+                handleReorder(issue.contentType);
+                break;
+        }
+    }
+
+    tasks.push(ConvertTask {ConvertTaskType::PLAYER, wfile->getPlayerFile()});
+}
+
 WorldConverter::WorldConverter(
     const std::shared_ptr<WorldFiles>& worldFiles,
     const Content* content,
-    std::shared_ptr<ContentReport> report
+    std::shared_ptr<ContentReport> reportPtr,
+    bool upgradeMode
 )
     : wfile(worldFiles),
-      report(std::move(report)),
-      content(content) {
-    fs::path regionsFolder =
-        wfile->getRegions().getRegionsFolder(REGION_LAYER_VOXELS);
-    if (!fs::is_directory(regionsFolder)) {
-        logger.error() << "nothing to convert";
-        return;
-    }
-    tasks.push(convert_task {convert_task_type::player, wfile->getPlayerFile()}
-    );
-    for (const auto& file : fs::directory_iterator(regionsFolder)) {
-        tasks.push(convert_task {convert_task_type::region, file.path()});
+      report(std::move(reportPtr)),
+      content(content),
+      upgradeMode(upgradeMode)
+{
+    if (upgradeMode) {
+        createUpgradeTasks();
+    } else {
+        createConvertTasks();
     }
 }
 
@@ -60,9 +128,11 @@ std::shared_ptr<Task> WorldConverter::startTask(
     const Content* content,
     const std::shared_ptr<ContentReport>& report,
     const runnable& onDone,
+    bool upgradeMode,
     bool multithreading
 ) {
-    auto converter = std::make_shared<WorldConverter>(worldFiles, content, report);
+    auto converter = std::make_shared<WorldConverter>(
+        worldFiles, content, report, upgradeMode);
     if (!multithreading) {
         converter->setOnComplete([=]() {
             converter->write();
@@ -70,15 +140,15 @@ std::shared_ptr<Task> WorldConverter::startTask(
         });
         return converter;
     }
-    auto pool = std::make_shared<util::ThreadPool<convert_task, int>>(
+    auto pool = std::make_shared<util::ThreadPool<ConvertTask, int>>(
         "converter-pool",
         [=]() { return std::make_shared<ConverterWorker>(converter); },
         [=](int&) {}
     );
     auto& converterTasks = converter->tasks;
     while (!converterTasks.empty()) {
-        const convert_task& task = converterTasks.front();
-        auto ptr = std::make_shared<convert_task>(task);
+        const ConvertTask& task = converterTasks.front();
+        auto ptr = std::make_shared<ConvertTask>(task);
         pool->enqueueJob(ptr);
         converterTasks.pop();
     }
@@ -89,19 +159,27 @@ std::shared_ptr<Task> WorldConverter::startTask(
     return pool;
 }
 
-void WorldConverter::convertRegion(const fs::path& file) const {
-    int x, z;
-    std::string name = file.stem().string();
-    if (!WorldRegions::parseRegionFilename(name, x, z)) {
-        logger.error() << "could not parse name " << name;
-        return;
-    }
-    logger.info() << "converting region " << name;
-    wfile->getRegions().processRegionVoxels(x, z, [=](ubyte* data) {
-        if (report) {
-            Chunk::convert(data, report.get());
-        }
-        return true;
+void WorldConverter::upgradeSimple(const fs::path& file, int x, int z) const {
+    throw std::runtime_error("unsupported region format");
+}
+
+void WorldConverter::upgradeVoxels(const fs::path& file, int x, int z) const {
+    throw std::runtime_error("unsupported region format");
+}
+
+void WorldConverter::convertVoxels(const fs::path& file, int x, int z) const {
+    logger.info() << "converting voxels region " << x << "_" << z;
+    wfile->getRegions().processRegion(x, z, REGION_LAYER_VOXELS, CHUNK_DATA_LEN,
+    [=](std::unique_ptr<ubyte[]> data, uint32_t*) {
+        Chunk::convert(data.get(), report.get());
+        return data;
+    });
+}
+
+void WorldConverter::convertInventories(const fs::path& file, int x, int z) const {
+    logger.info() << "converting inventories region " << x << "_" << z;
+    wfile->getRegions().processInventories(x, z, [=](Inventory* inventory) {
+        inventory->convert(report.get());
     });
 }
 
@@ -112,14 +190,23 @@ void WorldConverter::convertPlayer(const fs::path& file) const {
     files::write_json(file, map.get());
 }
 
-void WorldConverter::convert(const convert_task& task) const {
+void WorldConverter::convert(const ConvertTask& task) const {
     if (!fs::is_regular_file(task.file)) return;
 
     switch (task.type) {
-        case convert_task_type::region:
-            convertRegion(task.file);
+        case ConvertTaskType::UPGRADE_SIMPLE:
+            upgradeSimple(task.file, task.x, task.z);
             break;
-        case convert_task_type::player:
+        case ConvertTaskType::UPGRADE_VOXELS:
+            upgradeVoxels(task.file, task.x, task.z);
+            break;
+        case ConvertTaskType::VOXELS:
+            convertVoxels(task.file, task.x, task.z);
+            break;
+        case ConvertTaskType::INVENTORIES:
+            convertInventories(task.file, task.x, task.z);
+            break;
+        case ConvertTaskType::PLAYER:
             convertPlayer(task.file);
             break;
     }
@@ -129,7 +216,7 @@ void WorldConverter::convertNext() {
     if (tasks.empty()) {
         throw std::runtime_error("no more regions to convert");
     }
-    convert_task task = tasks.front();
+    ConvertTask task = tasks.front();
     tasks.pop();
     tasksDone++;
 
@@ -157,7 +244,7 @@ bool WorldConverter::isActive() const {
 
 void WorldConverter::write() {
     logger.info() << "writing world";
-    wfile->write(nullptr, content);
+    wfile->write(nullptr, upgradeMode ? nullptr : content);
 }
 
 void WorldConverter::waitForEnd() {
diff --git a/src/files/WorldConverter.hpp b/src/files/WorldConverter.hpp
index 3b14942a..d8a3ce5f 100644
--- a/src/files/WorldConverter.hpp
+++ b/src/files/WorldConverter.hpp
@@ -6,6 +6,7 @@
 
 #include "delegates.hpp"
 #include "interfaces/Task.hpp"
+#include "files/world_regions_fwd.hpp"
 #include "typedefs.hpp"
 
 namespace fs = std::filesystem;
@@ -14,32 +15,59 @@ class Content;
 class ContentReport;
 class WorldFiles;
 
-enum class convert_task_type { region, player };
+enum class ConvertTaskType {
+    /// @brief rewrite voxels region indices
+    VOXELS,
+    /// @brief rewrite inventories region indices
+    INVENTORIES,
+    /// @brief rewrite player
+    PLAYER,
+    /// @brief refresh region file version
+    UPGRADE_SIMPLE,
+    /// @brief rewrite voxels region file to new format
+    UPGRADE_VOXELS,
+};
 
-struct convert_task {
-    convert_task_type type;
+struct ConvertTask {
+    ConvertTaskType type;
     fs::path file;
+
+    /// @brief region coords
+    int x, z;
 };
 
 class WorldConverter : public Task {
     std::shared_ptr<WorldFiles> wfile;
     std::shared_ptr<ContentReport> const report;
     const Content* const content;
-    std::queue<convert_task> tasks;
+    std::queue<ConvertTask> tasks;
     runnable onComplete;
     uint tasksDone = 0;
+    bool upgradeMode;
 
+    void upgradeSimple(const fs::path& file, int x, int z) const;
+    void upgradeVoxels(const fs::path& file, int x, int z) const;
     void convertPlayer(const fs::path& file) const;
-    void convertRegion(const fs::path& file) const;
+    void convertVoxels(const fs::path& file, int x, int z) const;
+    void convertInventories(const fs::path& file, int x, int z) const;
+
+    void addRegionsTasks(
+        RegionLayerIndex layerid,
+        ConvertTaskType taskType
+    );
+
+    void createUpgradeTasks();
+    void createConvertTasks();
 public:
     WorldConverter(
         const std::shared_ptr<WorldFiles>& worldFiles,
         const Content* content,
-        std::shared_ptr<ContentReport> report
+        std::shared_ptr<ContentReport> report,
+        bool upgradeMode
     );
     ~WorldConverter();
 
-    void convert(const convert_task& task) const;
+    void convert(const ConvertTask& task) const;
     void convertNext();
     void setOnComplete(runnable callback);
     void write();
@@ -56,6 +84,7 @@ public:
         const Content* content,
         const std::shared_ptr<ContentReport>& report,
         const runnable& onDone,
+        bool upgradeMode,
         bool multithreading
     );
 };
diff --git a/src/files/WorldFiles.cpp b/src/files/WorldFiles.cpp
index 01b9cb77..54e96759 100644
--- a/src/files/WorldFiles.cpp
+++ b/src/files/WorldFiles.cpp
@@ -74,7 +74,9 @@ fs::path WorldFiles::getPacksFile() const {
     return directory / fs::path("packs.list");
 }
 
-void WorldFiles::write(const World* world, const Content* content) {
+void WorldFiles::write(
+    const World* world, const Content* content
+) {
     if (world) {
         writeWorldInfo(world->getInfo());
         if (!fs::exists(getPacksFile())) {
@@ -84,8 +86,10 @@ void WorldFiles::write(const World* world, const Content* content) {
     if (generatorTestMode) {
         return;
     }
-    writeIndices(content->getIndices());
-    regions.write();
+    if (content) {
+        writeIndices(content->getIndices());
+    }
+    regions.writeAll();
 }
 
 void WorldFiles::writePacks(const std::vector<ContentPack>& packs) {
diff --git a/src/files/WorldRegions.cpp b/src/files/WorldRegions.cpp
index cd0955c1..f3e1fd88 100644
--- a/src/files/WorldRegions.cpp
+++ b/src/files/WorldRegions.cpp
@@ -101,9 +101,8 @@ void WorldRegions::put(
 }
 
 static std::unique_ptr<ubyte[]> write_inventories(
-    Chunk* chunk, uint& datasize
+    const chunk_inventories_map& inventories, uint32_t& datasize
 ) {
-    auto& inventories = chunk->inventories;
     ByteBuilder builder;
     builder.putInt32(inventories.size());
     for (auto& entry : inventories) {
@@ -120,6 +119,22 @@ static std::unique_ptr<ubyte[]> write_inventories(
     return data;
 }
 
+static chunk_inventories_map load_inventories(const ubyte* src, uint32_t size) {
+    chunk_inventories_map inventories;
+    ByteReader reader(src, size);
+    auto count = reader.getInt32();
+    for (int i = 0; i < count; i++) {
+        uint index = reader.getInt32();
+        uint size = reader.getInt32();
+        auto map = json::from_binary(reader.pointer(), size);
+        reader.skip(size);
+        auto inv = std::make_shared<Inventory>(0, 0);
+        inv->deserialize(map.get());
+        inventories[index] = inv;
+    }
+    return inventories;
+}
+
 void WorldRegions::put(Chunk* chunk, std::vector<ubyte> entitiesData) {
     assert(chunk != nullptr);
     if (!chunk->flags.lighted) {
@@ -150,7 +165,7 @@ void WorldRegions::put(Chunk* chunk, std::vector<ubyte> entitiesData) {
     // Writing block inventories
     if (!chunk->inventories.empty()) {
         uint datasize;
-        auto data = write_inventories(chunk, datasize);
+        auto data = write_inventories(chunk->inventories, datasize);
         put(chunk->x,
             chunk->z,
             REGION_LAYER_INVENTORIES,
@@ -195,24 +210,25 @@ std::unique_ptr<light_t[]> WorldRegions::getLights(int x, int z) {
 }
 
 chunk_inventories_map WorldRegions::fetchInventories(int x, int z) {
-    chunk_inventories_map meta;
     uint32_t bytesSize;
     auto bytes = layers[REGION_LAYER_INVENTORIES].getData(x, z, bytesSize);
     if (bytes == nullptr) {
-        return meta;
+        return {};
     }
-    ByteReader reader(bytes, bytesSize);
-    auto count = reader.getInt32();
-    for (int i = 0; i < count; i++) {
-        uint index = reader.getInt32();
-        uint size = reader.getInt32();
-        auto map = json::from_binary(reader.pointer(), size);
-        reader.skip(size);
-        auto inv = std::make_shared<Inventory>(0, 0);
-        inv->deserialize(map.get());
-        meta[index] = inv;
-    }
-    return meta;
+    return load_inventories(bytes, bytesSize);
+}
+
+void WorldRegions::processInventories(
+    int x, int z, const inventoryproc& func
+) {
+    processRegion(x, z, REGION_LAYER_INVENTORIES, 0,
+    [=](std::unique_ptr<ubyte[]> data, uint32_t* size) {
+        auto inventories = load_inventories(data.get(), *size);
+        for (const auto& [_, inventory] : inventories) {
+            func(inventory.get());
+        }
+        return write_inventories(inventories, *size);
+    });
 }
 
 dynamic::Map_sptr WorldRegions::fetchEntities(int x, int z) {
@@ -231,8 +247,10 @@ dynamic::Map_sptr WorldRegions::fetchEntities(int x, int z) {
     return map;
 }
 
-void WorldRegions::processRegionVoxels(int x, int z, const regionproc& func) {
-    auto& layer = layers[REGION_LAYER_VOXELS];
+void WorldRegions::processRegion(
+    int x, int z, RegionLayerIndex layerid, uint32_t dataLen, const regionproc& func
+) {
+    auto& layer = layers[layerid];
     if (layer.getRegion(x, z)) {
         throw std::runtime_error("not implemented for in-memory regions");
     }
@@ -250,25 +268,29 @@ void WorldRegions::processRegionVoxels(int x, int z, const regionproc& func) {
             if (data == nullptr) {
                 continue;
             }
-            data = compression::decompress(
-                data.get(), length, CHUNK_DATA_LEN, layer.compression
-            );
-            if (func(data.get())) {
-                put(gx,
-                    gz,
-                    REGION_LAYER_VOXELS,
-                    std::move(data),
-                    CHUNK_DATA_LEN);
+            uint32_t totalLength = dataLen;
+            if (layer.compression != compression::Method::NONE) {
+                if (dataLen == 0) {
+                    throw std::invalid_argument("invalid data length");
+                }
+                data = compression::decompress(
+                    data.get(), length, dataLen, layer.compression
+                );
+            } else {
+                totalLength = length;
+            }
+            if (auto writeData = func(std::move(data), &totalLength)) {
+                put(gx, gz, layerid, std::move(writeData), totalLength);
             }
         }
     }
 }
 
-fs::path WorldRegions::getRegionsFolder(int layer) const {
-    return layers[layer].folder;
+const fs::path& WorldRegions::getRegionsFolder(RegionLayerIndex layerid) const {
+    return layers[layerid].folder;
 }
 
-void WorldRegions::write() {
+void WorldRegions::writeAll() {
     for (auto& layer : layers) {
         fs::create_directories(layer.folder);
         layer.writeAll();
diff --git a/src/files/WorldRegions.hpp b/src/files/WorldRegions.hpp
index eb2e803a..e4060002 100644
--- a/src/files/WorldRegions.hpp
+++ b/src/files/WorldRegions.hpp
@@ -16,6 +16,7 @@
 #include "maths/voxmaths.hpp"
 #include "coders/compression.hpp"
 #include "files.hpp"
+#include "world_regions_fwd.hpp"
 
 #define GLM_ENABLE_EXPERIMENTAL
 #include <glm/gtx/hash.hpp>
@@ -24,15 +25,6 @@ namespace fs = std::filesystem;
 
 inline constexpr uint REGION_HEADER_SIZE = 10;
 
-enum RegionLayerIndex : uint {
-    REGION_LAYER_VOXELS = 0,
-    REGION_LAYER_LIGHTS,
-    REGION_LAYER_INVENTORIES,
-    REGION_LAYER_ENTITIES,
-    
-    REGION_LAYERS_COUNT
-};
-
 inline constexpr uint REGION_SIZE_BIT = 5;
 inline constexpr uint REGION_SIZE = (1 << (REGION_SIZE_BIT));
 inline constexpr uint REGION_CHUNKS_COUNT = ((REGION_SIZE) * (REGION_SIZE));
@@ -75,8 +67,10 @@ struct regfile {
 };
 
 using regionsmap = std::unordered_map<glm::ivec2, std::unique_ptr<WorldRegion>>;
-using regionproc = std::function<bool(ubyte*)>;
+using regionproc = std::function<std::unique_ptr<ubyte[]>(std::unique_ptr<ubyte[]>,uint32_t*)>;
+using inventoryproc = std::function<void(Inventory*)>;
 
+/// @brief Region file pointer keeping inUse flag on until destroyed
 class regfile_ptr {
     regfile* file;
     std::condition_variable* cv;
@@ -209,6 +203,10 @@ public:
         size_t size
     );
 
+    /// @brief Get chunk voxels data
+    /// @param x chunk.x
+    /// @param z chunk.z
+    /// @return voxels data buffer or nullptr
     std::unique_ptr<ubyte[]> getVoxels(int x, int z);
 
     /// @brief Get cached lights for chunk at x,z
@@ -217,13 +215,30 @@ public:
     
     chunk_inventories_map fetchInventories(int x, int z);
     
+    /// @brief Load saved entities data for chunk
+    /// @param x chunk.x
+    /// @param z chunk.z
+    /// @return map with entities list as "data"
     dynamic::Map_sptr fetchEntities(int x, int z);
 
-    void processRegionVoxels(int x, int z, const regionproc& func);
+    /// @brief Load, process and save processed region chunks data
+    /// @param x region X
+    /// @param z region Z
+    /// @param layerid regions layer index
+    /// @param func processing callback
+    void processRegion(
+        int x, int z, RegionLayerIndex layerid, uint32_t dataLen, const regionproc& func);
 
-    fs::path getRegionsFolder(int layer) const;
+    void processInventories(
+        int x, int z, const inventoryproc& func);
 
-    void write();
+    /// @brief Get regions directory by layer index
+    /// @param layerid layer index
+    /// @return directory path
+    const fs::path& getRegionsFolder(RegionLayerIndex layerid) const;
+
+    /// @brief Write all region layers
+    void writeAll();
 
     /// @brief Extract X and Z from 'X_Z.bin' region file name.
     /// @param name source region file name
diff --git a/src/files/world_regions_fwd.hpp b/src/files/world_regions_fwd.hpp
new file mode 100644
index 00000000..e0398641
--- /dev/null
+++ b/src/files/world_regions_fwd.hpp
@@ -0,0 +1,12 @@
+#pragma once
+
+#include "typedefs.hpp"
+
+enum RegionLayerIndex : uint {
+    REGION_LAYER_VOXELS = 0,
+    REGION_LAYER_LIGHTS,
+    REGION_LAYER_INVENTORIES,
+    REGION_LAYER_ENTITIES,
+    
+    REGION_LAYERS_COUNT
+};
diff --git a/src/items/Inventory.cpp b/src/items/Inventory.cpp
index c2bc16ed..309ac57f 100644
--- a/src/items/Inventory.cpp
+++ b/src/items/Inventory.cpp
@@ -81,6 +81,15 @@ std::unique_ptr<dynamic::Map> Inventory::serialize() const {
     return map;
 }
 
+void Inventory::convert(const ContentReport* report) {
+    for (auto& slot : slots) {
+        itemid_t id = slot.getItemId();
+        itemid_t replacement = report->items.getId(id);
+        slot.set(ItemStack(replacement, slot.getCount()));
+    }
+}
+
+// TODO: remove
 void Inventory::convert(dynamic::Map* data, const ContentReport* report) {
     auto slotsarr = data->list("slots");
     for (size_t i = 0; i < slotsarr->size(); i++) {
diff --git a/src/items/Inventory.hpp b/src/items/Inventory.hpp
index 260ec08c..0f80fb26 100644
--- a/src/items/Inventory.hpp
+++ b/src/items/Inventory.hpp
@@ -42,6 +42,7 @@ public:
     /* serializing inventory */
     std::unique_ptr<dynamic::Map> serialize() const override;
 
+    void convert(const ContentReport* report);
     static void convert(dynamic::Map* data, const ContentReport* report);
 
     inline void setId(int64_t id) {
diff --git a/src/items/ItemStack.cpp b/src/items/ItemStack.cpp
index 932f4417..99cb0a0e 100644
--- a/src/items/ItemStack.cpp
+++ b/src/items/ItemStack.cpp
@@ -16,6 +16,9 @@ void ItemStack::set(const ItemStack& item) {
     if (count == 0) {
         this->item = 0;
     }
+    if (this->item == 0) {
+        count = 0;
+    }
 }
 
 bool ItemStack::accepts(const ItemStack& other) const {
diff --git a/src/logic/EngineController.cpp b/src/logic/EngineController.cpp
index 91e77220..8cb53f28 100644
--- a/src/logic/EngineController.cpp
+++ b/src/logic/EngineController.cpp
@@ -59,6 +59,7 @@ std::shared_ptr<Task> create_converter(
             menu->setPage("main", false);
             engine->getGUI()->postRunnable([=]() { postRunnable(); });
         },
+        report->isUpgradeRequired(),
         true
     );
 }