Yes, I would roll back to v.10 if it is convenient to do so.
If I remember correctly the upgrade from 10 to 11 was a bit “tweaky” (at least in my case). Secondly, the MySQL issue was only a Warning and I do not recall that it was service-affecting. In any event, in my opinion, it’s best not to leave those holes to fester and possibly create problems later.
Back to the upgrade: The biggest step in preparation involved the dependencies:
sudo apt-get update
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
Since you might be “peeling an onion” here, can you take a look at Mitch’s post and run down the list of items to check in the upgrade process? Daniel Pan also lists the “official” dependencies here.
As a side bar, assuming you revert to v.10.0.1, I simply do not know if it is safe to do the whole upgrade to 11.0.12 in one fell swoop. I am in the habit of doing Seafile upgrades incrementally. I will have to leave the issue of a large jump to another commenter or post on this forum.
I hope this helps. Good luck!