Seahub error after upgrade to 7.1.1

After upgrading, seahub gives me this:
2020-01-01 21:04:53,736 [ERROR] django.request:135 handle_uncaught_exception Internal Server
Error: /
Traceback (most recent call last):
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/core/handlers/exception.py”, line 41, in inner
response = get_response(request)
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/core/handlers/base.py”, line 244, in _legacy_get_response
response = middleware_method(request)
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/middleware/locale.py”, line 24, in process_request
i18n_patterns_used, prefixed_default_language = is_language_prefix_patterns_used(urlconf)
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/conf/urls/i18n.py”, line 29, in is_language_prefix_patterns_used
for url_pattern in get_resolver(urlconf).url_patterns:
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/utils/functional.py”, line 35, in get
res = instance.dict[self.name] = self.func(instance)
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/urls/resolvers.py”, line 407, in url_patterns
patterns = getattr(self.urlconf_module, “urlpatterns”, self.urlconf_module)
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/utils/functional.py”, line 35, in get
res = instance.dict[self.name] = self.func(instance)
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/urls/resolvers.py”, line 400, in urlconf_module
return import_module(self.urlconf_name)
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 958, in _find_and_load_unlocked
File “”, line 673, in _load_unlocked
File “”, line 673, in exec_module
File “”, line 222, in _call_with_frames_removed
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/seahub/utils/rooturl.py”, line 41, in
url(r’^%s’ % settings.SITE_ROOT[1:], include(settings.SITE_ROOT_URLCONF)),
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/django/conf/urls/init.py”, line 50, in include
urlconf_module = import_module(urlconf_module)
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 958, in _find_and_load_unlocked
File “”, line 673, in _load_unlocked
File “”, line 673, in exec_module
File “”, line 222, in _call_with_frames_removed
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/seahub/urls.py”, line 8, in
from seahub.views.sysadmin import *
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/seahub/views/sysadmin.py”, line 13, in
from openpyxl import load_workbook
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/openpyxl/init.py”, line 6, in
from openpyxl.workbook import Workbook
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/openpyxl/workbook/init.py”, line 4, in
from .workbook import Workbook
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/openpyxl/workbook/workbook.py”, line 7, in
from openpyxl.worksheet.worksheet import Worksheet
File “/home/thomas/seafile/seafile-server-7.1.1/seahub/thirdpart/openpyxl/worksheet/worksheet.py”, line 392
return f"{get_column_letter(min_col)}{min_row}:{get_column_letter(max_col)}{max_row}"
^
SyntaxError: invalid syntax
Thank you!

I see you are using Python 3.5. Python 3.6 or 3.7 is needed for 7.1.1.

Thank you!
I installed python3.6 from source and python --version now shows “Python 3.6.9”.
But in the seahub log there is “File “/usr/lib/python3.5/importlib/init.py”, line 126, in import_module” and seahub does not start…