https://github.com/haiwen/seafile-client/issues/1615

upstream won't change the minimum version soon
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3bb58761..58af8e15 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,4 +1,4 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.9)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.20)
 
 PROJECT(seafile-client)
 SET(SEAFILE_CLIENT_VERSION_MAJOR 9)
diff --git a/extensions/CMakeLists.txt b/extensions/CMakeLists.txt
index 25fc432b..e92f2301 100644
--- a/extensions/CMakeLists.txt
+++ b/extensions/CMakeLists.txt
@@ -1,4 +1,4 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.6)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.20)
 PROJECT(seafile_shell_ext)
 
 OPTION(X32 "Build 32 bit instead of 64bit dll" OFF)
diff --git a/fsplugin/CMakeLists.txt b/fsplugin/CMakeLists.txt
index 1e546c40..0faba566 100644
--- a/fsplugin/CMakeLists.txt
+++ b/fsplugin/CMakeLists.txt
@@ -1,4 +1,4 @@
-CMAKE_MINIMUM_REQUIRED(VERSION 2.8.11)
+CMAKE_MINIMUM_REQUIRED(VERSION 3.20)
 
 PROJECT(seafile-fsplugin)
 SET(PROJECT_VERSION "1.0.0")