diff --git a/CHANGELOG.md b/CHANGELOG.md
new file mode 100644
index 0000000..a0c3db7
--- /dev/null
+++ b/CHANGELOG.md
@@ -0,0 +1,18 @@
+# Changelog
+
+## LMDBAL 0.3.1 (April 14, 2023)
+### Bug fixes
+- build with qt5 now is possible again
+
+### Improvements
+- exception documentation
+
+## LMDBAL 0.3.0 (April 12, 2023)
+### New features
+- transaction functions
+
+### Improvements
+- initial documentation
+- cache unit testing
+- transactions unit testing
+- serialization unit testing
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 4d719ce..81c12f8 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,7 @@
 cmake_minimum_required(VERSION 3.16)
 
 project(LMDBAL
-  VERSION 0.3.0
+  VERSION 0.3.1
   DESCRIPTION "LMDB (Lightning Memory-Mapped Database Manager) Abstraction Layer"
   LANGUAGES CXX
 )
diff --git a/packaging/Archlinux/PKGBUILD b/packaging/Archlinux/PKGBUILD
index f5d1431..63457c6 100644
--- a/packaging/Archlinux/PKGBUILD
+++ b/packaging/Archlinux/PKGBUILD
@@ -1,6 +1,6 @@
 # Maintainer: Yury Gubich <blue@macaw.me>
 pkgname=lmdbal
-pkgver=0.3.0
+pkgver=0.3.1
 pkgrel=1
 pkgdesc="LMDB Abstraction Layer, qt5 version"
 arch=('i686' 'x86_64')
@@ -11,7 +11,7 @@ makedepends=('cmake>=3.16')
 optdepends=()
 
 source=("$pkgname-$pkgver.tar.gz::https://git.macaw.me/blue/lmdbal/archive/$pkgver.tar.gz")
-sha256sums=('SKIP')
+sha256sums=('df1a9687d81d609d160754285f2613d7e07fc6deb781d0fb0084e4857ea82e95')
 build() {
         cd "$srcdir/$pkgname"
         cmake . -D CMAKE_INSTALL_PREFIX=/usr -D CMAKE_BUILD_TYPE=Release -D QT_VERSION_MAJOR=5
@@ -19,5 +19,5 @@ build() {
 }
 package() {
         cd "$srcdir/$pkgname"
-        cmake --install . --prefix $pkgdir/
+        DESTDIR="$pkgdir/" cmake --install .
 }
diff --git a/src/exceptions.h b/src/exceptions.h
index 88eb510..c583c9b 100644
--- a/src/exceptions.h
+++ b/src/exceptions.h
@@ -25,18 +25,29 @@
 
 namespace LMDBAL {
 
+/**
+ * \brief Parent abstract class for all LMDBAL exceptions
+ */
 class Exception : public std::exception {
 public:
     Exception();
     virtual ~Exception();
 
-    virtual std::string getMessage() const = 0;
+    virtual std::string getMessage() const = 0; /**<\brief returns exception message*/
 
-    const char* what() const noexcept( true );
+    const char* what() const noexcept( true ) override;
 };
 
+/**
+ * \brief Thrown if LMDBAL had issues creating or opening database directory
+ */
 class Directory: public Exception {
 public:
+    /**
+     * \brief Creates exception
+     *
+     * \param path  - path of the directory that was supposed to be used to store the database
+     */
     Directory(const std::string& path);
 
     std::string getMessage() const;
@@ -44,9 +55,19 @@ private:
     std::string path;
 };
 
+/**
+ * \brief Thrown if something in the database was called on closed state and it is not supported
+ */
 class Closed : public Exception {
 public:
-    Closed(const std::string& p_operation, const std::string& dbName, const std::optional<std::string>& tableName = std::nullopt);
+    /**
+     * \brief Creates exception
+     *
+     * \param operation - text name of the method that was called on closed database
+     * \param dbName    - name of the database
+     * \param tableName - name of the storage which called that method, abscent if it's untracable or if it's thrown by the database
+     */
+    Closed(const std::string& operation, const std::string& dbName, const std::optional<std::string>& tableName = std::nullopt);
 
     std::string getMessage() const;
 private:
@@ -55,8 +76,17 @@ private:
     std::optional<std::string> tableName;
 };
 
+/**
+ * \brief Thrown if something in the database was called on opened state and it is not supported
+ */
 class Opened : Exception {
 public:
+    /**
+     * \brief Creates exception
+     *
+     * \param action    - text name of the method that was called on opened database
+     * \param dbName    - name of the database
+     */
     Opened(const std::string& dbName, const std::string& action);
 
     std::string getMessage() const;
@@ -65,8 +95,18 @@ private:
     std::string action;
 };
 
+/**
+ * \brief Thrown if something in the database was not found
+ */
 class NotFound : public Exception {
 public:
+    /**
+     * \brief Creates exception
+     *
+     * \param key       - record key that was not found
+     * \param dbName    - name of the database
+     * \param tableName - name of the storage that was looked for a record
+     */
     NotFound(const std::string& key, const std::string& dbName, const std::string& tableName);
 
     std::string getMessage() const;
@@ -76,8 +116,17 @@ private:
     std::string tableName;
 };
 
+/**
+ * \brief Thrown if there was attempt to define storages with conflicting names
+ */
 class StorageDuplicate : public Exception {
 public:
+    /**
+     * \brief Creates exception
+     *
+     * \param dbName    - name of the database
+     * \param tableName - that name that was conflicting
+     */
     StorageDuplicate(const std::string& dbName, const std::string& tableName);
 
     std::string getMessage() const;
@@ -86,8 +135,18 @@ private:
     std::string tableName;
 };
 
+/**
+ * \brief Thrown if there was a key conflict in one of the storages
+ */
 class Exist : public Exception {
 public:
+    /**
+     * \brief Creates exception
+     *
+     * \param key       - record key that caused the conflict
+     * \param dbName    - name of the database
+     * \param tableName - name of the storage that was operated with
+     */
     Exist(const std::string& key, const std::string& dbName, const std::string& tableName);
 
     std::string getMessage() const;
@@ -97,8 +156,18 @@ private:
     std::string tableName;
 };
 
+/**
+ * \brief Thrown if something unexpected happened
+ */
 class Unknown : public Exception {
 public:
+    /**
+     * \brief Creates exception
+     *
+     * \param message   - text description of the error, most of the times contains the result of <a class="el" href="http://www.lmdb.tech/doc/group__mdb.html#ga569e66c1e3edc1a6016b86719ee3d098">mdb_strerror</a>
+     * \param dbName    - name of the database
+     * \param tableName - name of the storage that was operated with, abscent if the operation was with the database itself
+     */
     Unknown(const std::string& dbName, const std::string& message, const std::optional<std::string>& tableName = std::nullopt);
 
     std::string getMessage() const;
diff --git a/src/operators.hpp b/src/operators.hpp
index 8adea66..80353ac 100644
--- a/src/operators.hpp
+++ b/src/operators.hpp
@@ -75,21 +75,23 @@ QDataStream& operator >> (QDataStream &in, std::multimap<K, V>& container) {
     return in;
 }
 
-// template <class K, class V>
-// QDataStream& operator << (QDataStream &out, const std::pair<K, V>& pair) {
-//     out << pair.first;
-//     out << pair.second;
-//
-//     return out;
-// }
-//
-// template <class K, class V>
-// QDataStream& operator >> (QDataStream &in, std::pair<K, V>& container) {
-//     in >> container.first;
-//     in >> container.second;
-//
-//     return in;
-// }
+#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
+template <class K, class V>
+QDataStream& operator << (QDataStream &out, const std::pair<K, V>& pair) {
+    out << pair.first;
+    out << pair.second;
+
+    return out;
+}
+
+template <class K, class V>
+QDataStream& operator >> (QDataStream &in, std::pair<K, V>& container) {
+    in >> container.first;
+    in >> container.second;
+
+    return in;
+}
+#endif
 
 template <class K>
 QDataStream& operator << (QDataStream &out, const std::set<K>& container) {