diff --git a/README.md b/README.md
index eaa719e..55337f3 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,4 @@
-English | [Deutsch](./readme.i18n/README.de_DE.md) | [中文（简体字）](./readme.i18n/README.zh_CN.md) | [中文（正體字）](./readme.i18n/README.zh_TW.md) | [中文（香港字）](./readme.i18n/README.zh_HK.md)
+English | [Deutsch](./readme.i18n/README.de-DE.md) | [中文（简体字）](./readme.i18n/README.zh-CN.md) | [中文（正體字）](./readme.i18n/README.zh-TW.md) | [中文（香港字）](./readme.i18n/README.zh-HK.md)
 
 # Cat-Printer
 
diff --git a/build-android/0-build-android.sh b/build-android/0-build-android.sh
index 61bf9e9..64c0913 100755
--- a/build-android/0-build-android.sh
+++ b/build-android/0-build-android.sh
@@ -4,6 +4,6 @@ version=`cat ../version`
 p4a apk --private .. --dist_name="cat-printer" --package="io.github.naitlee.catprinter" --name="Cat Printer" \
     --icon=icon.png --version=$version --bootstrap=webview --window --requirements="`cat build-deps.txt`" \
     --blacklist-requirements=sqlite3,openssl --port=8095 --arch=arm64-v8a --blacklist="blacklist.txt" \
-    --presplash=blank.png --presplash-color=black --add-source="advancedwebview" --orientation=user \
+    --presplash=blank.png --presplash-color=black --add-source="advancedwebview" --manifest-orientation=user \
     --permission=BLUETOOTH --permission=BLUETOOTH_SCAN --permission=BLUETOOTH_CONNECT \
     --permission=BLUETOOTH_ADMIN --permission=ACCESS_FINE_LOCATION --permission=ACCESS_COARSE_LOCATION $@
diff --git a/build-android/4-sign.sh b/build-android/4-sign.sh
index 1e055b2..11f7935 100755
--- a/build-android/4-sign.sh
+++ b/build-android/4-sign.sh
@@ -1,6 +1,6 @@
 #!/bin/sh
 version=`cat ../version`
-unsigned_apk=cat-printer-release-unsigned-$version-.apk
+unsigned_apk=cat-printer-release-unsigned-$version.apk
 signed_apk=cat-printer-android-$version.apk
 
 if {
diff --git a/build-android/manual-steps.md b/build-android/manual-steps.md
index 1830dd4..ee88f00 100644
--- a/build-android/manual-steps.md
+++ b/build-android/manual-steps.md
@@ -87,11 +87,13 @@ If you’re in China Mainland (you guessed it!), or prefer manual setup:
 
 - Pick a working mirror. Currently there’s [Tencent Cloud](https://mirrors.cloud.tencent.com/AndroidSDK/).
 
+- Pay attention to [required version of Android NDK](https://python-for-android.readthedocs.io/en/latest/quickstart/#basic-sdk-install), this will increase by time. It’s currently r25b.
+
 - Fetch & extract some archives, as shown in this table:
 
 | Archive file                        | Top-level dir inside    | Target directory                    |
 | ----------------------------------- | ----------------------- | ----------------------------------- |
-| `android-ndk-r23b-linux.zip`        | `android-ndk-r23b`      | `android/android-ndk-r23b`          |
+| `android-ndk-r25b-linux.zip`        | `android-ndk-r25b`      | `android/android-ndk-r25b`          |
 | `build-tools_r33-linux.zip`         | `android-13`            | `android/build-tools/33.0.0`        |
 | `commandlinetools-linux-8512546_latest.zip` | `cmdline-tools` | `android/cmdline-tools/latest`      |
 | `platform-30_r03.zip`               | `android-11`            | `android/platforms/android-30`      |
@@ -104,7 +106,7 @@ So after that you will get:
 
 ```
 android
-  ├── android-ndk-r23b
+  ├── android-ndk-r25b
   ├── build-tools
   │   └── 33.0.0
   ├── cmdline-tools
@@ -123,7 +125,7 @@ System doesn’t understand it. Let’s replace them as symlinks:
 ```bash
 # you may already have these from p4a guide
 ANDROIDSDK="$DIR_BUILD/android"
-ANDROIDNDK="$DIR_BUILD/android/android-ndk-r23b"
+ANDROIDNDK="$DIR_BUILD/android/android-ndk-r25b"
 # feel free to check this script
 python3 $DIR_GIT/Cat-Printer/build-android/fix-ndk-execs.py $ANDROIDNDK
 ```
@@ -185,7 +187,7 @@ We should glue them up by hand.
 echo '
 export DIR_BUILD="/mnt/data/@"
 export ANDROIDSDK="$DIR_BUILD/android"
-export ANDROIDNDK="$DIR_BUILD/android/android-ndk-r23b"
+export ANDROIDNDK="$DIR_BUILD/android/android-ndk-r25b"
 export ANDROIDAPI="30"
 export NDKAPI="21"' >> .bashrc
 
diff --git a/version b/version
index 229c8c8..7757ca2 100644
--- a/version
+++ b/version
@@ -1 +1 @@
-0.6.2.0
\ No newline at end of file
+0.6.2.1
\ No newline at end of file