diff --git a/python3/Dockerfile b/python3/Dockerfile
index 45e2e389f482bfa74197b1a1cc942102817463fa..ffcea95670a8e842b7fd2029531f2436d5dc4837 100644
--- a/python3/Dockerfile
+++ b/python3/Dockerfile
@@ -4,7 +4,7 @@
 # PLEASE DO NOT EDIT IT DIRECTLY.
 #
 
-FROM ubuntu:20.04
+FROM ubuntu:18.04
 MAINTAINER xt
 
 COPY sources.list /etc/apt/sources.list
@@ -85,7 +85,7 @@ RUN cd /usr/local/bin \
 	&& ln -s python3-config python-config
 
 # if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
-ENV PYTHON_PIP_VERSION 20.2.3
+ENV PYTHON_PIP_VERSION 20.2.4
 
 RUN set -ex; \
 	python get-pip.py \
diff --git a/python3/sources.list b/python3/sources.list
index ec973e3ea3a65c8c7b77132b3415f84fd986629a..82bd9625c805eae98764c57e76f03a3bb323a390 100644
--- a/python3/sources.list
+++ b/python3/sources.list
@@ -1,19 +1,19 @@
-# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ focal main restricted
-deb-src http://archive.ubuntu.com/ubuntu focal main restricted #Added by software-properties
-deb http://mirrors.aliyun.com/ubuntu/ focal main restricted
-deb-src http://mirrors.aliyun.com/ubuntu/ focal main restricted multiverse universe #Added by software-properties
-deb http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted
-deb-src http://mirrors.aliyun.com/ubuntu/ focal-updates main restricted multiverse universe #Added by software-properties
-deb http://mirrors.aliyun.com/ubuntu/ focal universe
-deb http://mirrors.aliyun.com/ubuntu/ focal-updates universe
-deb http://mirrors.aliyun.com/ubuntu/ focal multiverse
-deb http://mirrors.aliyun.com/ubuntu/ focal-updates multiverse
-deb http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse
-deb-src http://mirrors.aliyun.com/ubuntu/ focal-backports main restricted universe multiverse #Added by software-properties
-deb http://archive.canonical.com/ubuntu focal partner
-deb-src http://archive.canonical.com/ubuntu focal partner
-deb http://mirrors.aliyun.com/ubuntu/ focal-security main restricted
-deb-src http://mirrors.aliyun.com/ubuntu/ focal-security main restricted multiverse universe #Added by software-properties
-deb http://mirrors.aliyun.com/ubuntu/ focal-security universe
-deb http://mirrors.aliyun.com/ubuntu/ focal-security multiverse
+# deb cdrom:[Ubuntu 16.04 LTS _Xenial Xerus_ - Release amd64 (20160420.1)]/ bionic main restricted
+deb-src http://archive.ubuntu.com/ubuntu bionic main restricted #Added by software-properties
+deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted
+deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted multiverse universe #Added by software-properties
+deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted
+deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted multiverse universe #Added by software-properties
+deb http://mirrors.aliyun.com/ubuntu/ bionic universe
+deb http://mirrors.aliyun.com/ubuntu/ bionic-updates universe
+deb http://mirrors.aliyun.com/ubuntu/ bionic multiverse
+deb http://mirrors.aliyun.com/ubuntu/ bionic-updates multiverse
+deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
+deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse #Added by software-properties
+deb http://archive.canonical.com/ubuntu bionic partner
+deb-src http://archive.canonical.com/ubuntu bionic partner
+deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted
+deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted multiverse universe #Added by software-properties
+deb http://mirrors.aliyun.com/ubuntu/ bionic-security universe
+deb http://mirrors.aliyun.com/ubuntu/ bionic-security multiverse