UnicodeDecodeError after Upgrade from 7.0.5 to 7.1.3

since I upgraded to 7.1.3, Seahub gives me the following error when trying to access the site:

UnicodeDecodeError at /

‘ascii’ codec can’t decode byte 0xe3 in position 1: ordinal not in range(128)

I did all the steps required after an upgrade, including the database update script.
No errors reported, the only thing I had to do was to install “python3-django-captcha”, because seahub refused to start without this package.

I don’t know how to solve the above error, any help is appreciated.
Seafile is running on Ubuntu 18.04.4 with all latest updates installed.

ok it’s working now.
pip3 was unable to buiild some packages because of some missing libmemcache depedencies.
I installed the missing package (python3-pylibmc) using apt and everything is working fine again.
I also upgraded to Ubuntu Server 20.04 LTS and removed all the python2 stuff.

had similar issues but not exactly with libmemcache (pylibmc) and I end up upgrading my distro as well.