Upgrade issue from 7.0.5 too 7.1.5


i have ugprade from 7.0.5 to 7.1.5:
The Seafile will run in a lxc container on fedora 33:

I have download the latest version:
cd seafile/
wget XXXX://s3.eu-central-1.amazonaws.com/download.seadrive.org/seafile-server_7.1.5_x86-64.tar.gz
tar -xf seafile-server_7.1.5_x86-64.tar.gz
systemctl stop seafile
cp seahub.db seahub.db.2020-28-12
cd seafile-server-7.1.5/
cd upgrade/

if i start ./seahub.sh start the job will say:

root@nginx:/seafile/seafile-server-latest# ./seahub.sh start

LC_ALL is not set in ENV, set to en_US.UTF-8
Starting seahub at port 8000 …
Error:Seahub failed to start.
Please try to run “./seahub.sh start” again

if i try:
root@nginx:/seafile/seafile-server-latest# ./seahub.sh start-fastcgi 8000

LC_ALL is not set in ENV, set to en_US.UTF-8
Starting seahub (fastcgi) at …
Traceback (most recent call last):
File “/seafile/seafile-server-7.1.5/seahub/manage.py”, line 10, in
File “/seafile/seafile-server-7.1.5/seahub/thirdpart/django/core/management/init.py”, line 364, in execute_from_command_line
File “/seafile/seafile-server-7.1.5/seahub/thirdpart/django/core/management/init.py”, line 338, in execute
File “/seafile/seafile-server-7.1.5/seahub/thirdpart/django/init.py”, line 27, in setup
File “/seafile/seafile-server-7.1.5/seahub/thirdpart/django/apps/registry.py”, line 85, in populate
app_config = AppConfig.create(entry)
File “/seafile/seafile-server-7.1.5/seahub/thirdpart/django/apps/config.py”, line 94, in create
module = import_module(entry)
File “/usr/lib/python3.5/importlib/init.py”, line 126, in import_module
return _bootstrap._gcd_import(name[level:], package, level)
File “”, line 986, in _gcd_import
File “”, line 969, in _find_and_load
File “”, line 956, in _find_and_load_unlocked
ImportError: No module named ‘captcha’
Error:Seahub failed to start.

My pakets:
root@nginx:/seafile/seafile-server-latest# python --version
Python 2.7.12
root@nginx:/seafile/seafile-server-latest# python3 --version
Python 3.5.2


Did you install all python3 modules that are under manual?
Deploy with MySQL - Seafile admin manual
Here are the command from manual above:
apt-get update
apt-get install python3 python3-setuptools python3-pip -y
pip3 install --timeout=3600 Pillow pylibmc captcha jinja2 sqlalchemy django-pylibmc django-simple-captcha python3-ldap

In my case memcache modules were somehow not working, but since i do not use memcache for my seafile server i installed without these modules and 7.1.x works fine for me:
pip3 install --timeout=3600 Pillow captcha jinja2 sqlalchemy django-simple-captcha python3-ldap