diff --git a/.github/workflows/release.yaml b/.github/workflows/release.yaml
index c00793ec..d85ea588 100644
--- a/.github/workflows/release.yaml
+++ b/.github/workflows/release.yaml
@@ -69,7 +69,7 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install -y libclang-10-dev
-          sudo apt-get install -y libgtk2.0-dev libgtk-3-dev
+          sudo apt-get install -y libgtk-3-dev
 
       - name: Download engine
         uses: actions/download-artifact@v2
@@ -116,6 +116,7 @@ jobs:
 
     strategy:
       matrix:
+        # 5.15.3 doesn't have binary release
         qt5:
           - 5.9.5
           - 5.11.3
@@ -123,7 +124,6 @@ jobs:
           - 5.12.9
           - 5.14.2
           - 5.15.2
-          - 5.15.3
 
     steps:
       - name: Download engine
@@ -241,7 +241,7 @@ jobs:
           asset_name: libkime-qt-${{ matrix.qt6 }}.so
           asset_content_type: application/x-sharedlib
 
-  package-arch:
+  package-archive:
     needs:
       - build-other
       - build-qt5
@@ -263,7 +263,7 @@ jobs:
           - qt5: 5.14.2
             pkg: deb
             name: ubuntu-20.10
-          - qt5: 5.15.3
+          - qt5: 5.15.2
             pkg: deb
             name: ubuntu-22.04
           - qt5: 5.11.3
diff --git a/README.ko.md b/README.ko.md
index 1573fcd6..4de45f22 100644
--- a/README.ko.md
+++ b/README.ko.md
@@ -115,8 +115,6 @@ scripts/build.sh -ar
 패키지로 설치 하실 경우에는 필요 없을수도 있습니다.
 
 ```sh
-# GTK2 설치 시
-sudo gtk-query-immodules-2.0 --update-cache
 # GTK3 설치 시
 sudo gtk-query-immodules-3.0 --update-cache
 # GTK4 설치 시
@@ -164,7 +162,6 @@ kime은 kime 데몬을 위한 kime.desktop 파일을 /etc/xdg/autostart에 설
 참고로 필요하신 종속성만 있으면 됩니다
 예를들어 qt6를 사용하지 않으신다면 필요하지 않습니다.
 
-* gtk2
 * gtk3
 * gtk4
 * qt5
@@ -185,7 +182,6 @@ kime은 kime 데몬을 위한 kime.desktop 파일을 /etc/xdg/autostart에 설
 
 #### 선택적
 
-* gtk2
 * gtk3
 * gtk4
 * qtbase5-private
diff --git a/README.md b/README.md
index 442e019e..42d0e471 100644
--- a/README.md
+++ b/README.md
@@ -115,8 +115,6 @@ Every files needed for manual install is in `build/out` directory.
 Typically, this step is not necessary when kime is installed from binary package because most Linux distros does these steps themselves.
 
 ```sh
-# for gtk2
-sudo gtk-query-immodules-2.0 --update-cache
 # for gtk3
 sudo gtk-query-immodules-3.0 --update-cache
 # for gtk4
@@ -163,7 +161,6 @@ Read [CONFIGURATION.md](docs/CONFIGURATION.md) for detail options.
 
 These dependencies are optional depending on your environments. For example, qt6 is not required when it is not used.
 
-* gtk2
 * gtk3
 * gtk4
 * qt5
@@ -184,7 +181,6 @@ These dependencies are optional depending on your environments. For example, qt6
 
 #### Optional
 
-* gtk2
 * gtk3
 * gtk4
 * qtbase5-private
diff --git a/VERSION b/VERSION
index da6b0a8f..4a36342f 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.5.6
+3.0.0
diff --git a/build-docker/arch/Dockerfile b/build-docker/arch/Dockerfile
index 07b53b96..89f45acd 100644
--- a/build-docker/arch/Dockerfile
+++ b/build-docker/arch/Dockerfile
@@ -4,7 +4,7 @@ WORKDIR /opt/kime
 
 RUN pacman -Syu --noconfirm
 RUN pacman -S --noconfirm --needed rust cmake clang llvm libxcb cairo
-RUN pacman -S --noconfirm --needed gtk2 gtk3 gtk4
+RUN pacman -S --noconfirm --needed gtk3 gtk4
 RUN pacman -S --noconfirm --needed qt5-base qt6-base
 RUN pacman -S --noconfirm --needed git
 RUN mkdir -pv /opt/kime-out
diff --git a/build-docker/debian-buster/Dockerfile b/build-docker/debian-buster/Dockerfile
index 947bae52..b8c6229c 100644
--- a/build-docker/debian-buster/Dockerfile
+++ b/build-docker/debian-buster/Dockerfile
@@ -12,7 +12,7 @@ deb http://ftp.debian.org/debian buster-backports main\n\
 " > /etc/apt/sources.list
 RUN apt-get update
 RUN apt-get install -y build-essential git gcc clang libclang-dev cmake extra-cmake-modules pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qt5-default qtbase5-dev qtbase5-private-dev libqt5gui5
 RUN mkdir -pv /opt/kime-out
 
diff --git a/build-docker/ubuntu-18.04/Dockerfile b/build-docker/ubuntu-18.04/Dockerfile
index 3cfe388a..8a6e2991 100644
--- a/build-docker/ubuntu-18.04/Dockerfile
+++ b/build-docker/ubuntu-18.04/Dockerfile
@@ -9,7 +9,7 @@ RUN apt-get install -y curl apt-utils
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --no-modify-path --profile minimal
 RUN curl --proto '=https' https://github.com/Kitware/CMake/releases/download/v3.19.5/cmake-3.19.5-Linux-$(uname -m).sh | sh -s -- --skip-license --prefix=/usr
 RUN apt-get install -y build-essential git gcc libclang-10-dev pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qt5-default qtbase5-dev qtbase5-private-dev libqt5gui5
 RUN mkdir -pv /opt/kime-out
 
diff --git a/build-docker/ubuntu-20.04/Dockerfile b/build-docker/ubuntu-20.04/Dockerfile
index 4d86e1b8..59cccdbd 100644
--- a/build-docker/ubuntu-20.04/Dockerfile
+++ b/build-docker/ubuntu-20.04/Dockerfile
@@ -10,7 +10,7 @@ RUN apt-get install -y curl apt-utils
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --no-modify-path --profile minimal
 RUN rustc --version
 RUN apt-get install -y build-essential git gcc libclang-10-dev cmake extra-cmake-modules pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qtbase5-dev qtbase5-private-dev libqt5gui5
 RUN apt-get install -y libxcb-shape0-dev libxcb-xfixes0-dev
 RUN mkdir -pv /opt/kime-out
diff --git a/build-docker/ubuntu-20.10/Dockerfile b/build-docker/ubuntu-20.10/Dockerfile
index fa43798b..7a472edf 100644
--- a/build-docker/ubuntu-20.10/Dockerfile
+++ b/build-docker/ubuntu-20.10/Dockerfile
@@ -10,7 +10,7 @@ RUN apt-get install -y curl apt-utils
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --no-modify-path --profile minimal
 RUN rustc --version
 RUN apt-get install -y build-essential git gcc libclang-10-dev cmake extra-cmake-modules pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qtbase5-dev qtbase5-private-dev libqt5gui5
 RUN mkdir -pv /opt/kime-out
 
diff --git a/build-docker/ubuntu-21.04/Dockerfile b/build-docker/ubuntu-21.04/Dockerfile
index b4a5c261..eb42c68d 100644
--- a/build-docker/ubuntu-21.04/Dockerfile
+++ b/build-docker/ubuntu-21.04/Dockerfile
@@ -10,7 +10,7 @@ RUN apt-get install -y curl apt-utils
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --no-modify-path --profile minimal
 RUN rustc --version
 RUN apt-get install -y build-essential git gcc libclang-11-dev cmake extra-cmake-modules pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qtbase5-dev qtbase5-private-dev libqt5gui5 libxcb-render0-dev libxcb-shape0-dev libxcb-xfixes0-dev
 RUN mkdir -pv /opt/kime-out
 
diff --git a/build-docker/ubuntu-21.10/Dockerfile b/build-docker/ubuntu-21.10/Dockerfile
index 545ac904..e4c131fd 100644
--- a/build-docker/ubuntu-21.10/Dockerfile
+++ b/build-docker/ubuntu-21.10/Dockerfile
@@ -11,7 +11,7 @@ RUN apt-get install -y curl apt-utils
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --no-modify-path --profile minimal
 RUN rustc --version
 RUN apt-get install -y build-essential git gcc libclang-11-dev cmake extra-cmake-modules pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qtbase5-dev qtbase5-private-dev libqt5gui5
 RUN apt-get install -y libxcb-shape0-dev libxcb-xfixes0-dev
 RUN mkdir -pv /opt/kime-out
diff --git a/build-docker/ubuntu-22.04/Dockerfile b/build-docker/ubuntu-22.04/Dockerfile
index bac9427a..1d791a9a 100644
--- a/build-docker/ubuntu-22.04/Dockerfile
+++ b/build-docker/ubuntu-22.04/Dockerfile
@@ -11,7 +11,7 @@ RUN apt-get install -y curl apt-utils
 RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y --default-toolchain stable --no-modify-path --profile minimal
 RUN rustc --version
 RUN apt-get install -y build-essential git gcc libclang-11-dev cmake extra-cmake-modules pkg-config zstd
-RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk2.0-dev libgtk-3-dev libglib2.0 libxcb1
+RUN apt-get install -y libpango1.0-dev libcairo2-dev libgtk-3-dev libglib2.0 libxcb1
 RUN apt-get install -y qtbase5-dev qtbase5-private-dev libqt5gui5
 RUN apt-get install -y libxcb-shape0-dev libxcb-xfixes0-dev
 RUN mkdir -pv /opt/kime-out
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index 81065a7c..6f0a9775 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -1,6 +1,12 @@
 # CHANGELOG
 
-## Dev
+## Unreleased
+
+### Breaking
+
+### Improve
+
+## 3.0.0
 
 ### Breaking
 
diff --git a/scripts/build.sh b/scripts/build.sh
index 182b26a8..d25a12d2 100755
--- a/scripts/build.sh
+++ b/scripts/build.sh
@@ -76,7 +76,7 @@ while getopts hrda opt; do
                 KIME_BUILD_XIM=1
             fi
             KIME_BUILD_KIME=1
-            KIME_CMAKE_ARGS="-DENABLE_GTK2=ON -DENABLE_GTK3=ON -DENABLE_GTK4=ON -DENABLE_QT5=ON -DENABLE_QT6=ON $KIME_CMAKE_ARGS"
+            KIME_CMAKE_ARGS="-DENABLE_GTK3=ON -DENABLE_GTK4=ON -DENABLE_QT5=ON -DENABLE_QT6=ON $KIME_CMAKE_ARGS"
             ;;
     esac
 done
diff --git a/scripts/install.sh b/scripts/install.sh
index 6e588beb..5baefc18 100755
--- a/scripts/install.sh
+++ b/scripts/install.sh
@@ -41,10 +41,6 @@ if [ -z "$KIME_LIB_DIR" ]; then
     KIME_LIB_DIR=usr/lib
 fi
 
-if [ -z "$KIME_GTK2_DIR" ]; then
-    KIME_GTK2_DIR="$KIME_LIB_DIR/gtk-2.0/2.10.0/immodules"
-fi
-
 if [ -z "$KIME_GTK3_DIR" ]; then
     KIME_GTK3_DIR="$KIME_LIB_DIR/gtk-3.0/3.0.0/immodules"
 fi
@@ -102,7 +98,6 @@ install -Dm644 $KIME_OUT/*.desktop -t "$PREFIX/$KIME_AUTOSTART_DIR"
 install -Dm644 $KIME_OUT/icons/64x64/*.png -t "$PREFIX/$KIME_ICON_DIR/hicolor/64x64/apps"
 install -Dm755 $KIME_OUT/libkime_engine.so -t "$PREFIX/$KIME_LIB_DIR"
 
-install_if libkime-gtk2.so 755 -T "$KIME_GTK2_DIR/im-kime.so"
 install_if libkime-gtk3.so 755 -T "$KIME_GTK3_DIR/im-kime.so"
 install_if libkime-gtk4.so 755 -t "$KIME_GTK4_DIR"
 install_if libkime-qt5.so 755 -T "$KIME_QT5_DIR/plugins/platforminputcontexts/libkimeplatforminputcontextplugin.so"
diff --git a/src/engine/backends/hanja/src/lib.rs b/src/engine/backends/hanja/src/lib.rs
index e8812518..f27d9469 100644
--- a/src/engine/backends/hanja/src/lib.rs
+++ b/src/engine/backends/hanja/src/lib.rs
@@ -29,11 +29,7 @@ impl HanjaMode {
                     self.client = Some(client);
                     true
                 }
-                Err(err) => {
-                    #[cfg(debug_assertions)]
-                    eprintln!("Can't spawn candidate window {:#?}", err);
-                    false
-                }
+                Err(_err) => false,
             }
         } else {
             false