sudo apt-get install -y python3 python3-dev python3-setuptools python3-pip libmysqlclient-dev ldap-utils libldap2-dev
sudo apt-get install -y memcached libmemcached-dev
sudo pip3 install --timeout=3600 django==3.2. future==0.18. mysqlclient==2.1. \ pymysql pillow==10.0. pylibmc captcha==0.4 markupsafe==2.0.1 jinja2 sqlalchemy==2.0.18 \ psd-tools django-pylibmc django_simple_captcha==0.5. djangosaml2==1.5. pysaml2==7.2. pycryptodome==3.16. cffi==1.15.1 lxml python-ldap==3.4.3

Above is the solution, it seems after upgrade, some python libraries are missing, just re-install these libraries and

su seafile
./seafile.sh start

Everything gets back to normal.

After upgrading the system to Unbuntu update to 22.04, php-fpm can not start, with error

error while loading shared libraries: libwebp.so.6

It seems the shared library is missing. Then just find the current libwebp.so in your system,

find / libwebp.so
/usr/lib/x86_64-linux-gnu/libwebp.so
/usr/lib/x86_64-linux-gnu/libwebp.so.7

I just copy libwebp.so to libwebp.so.6, then problem solved.