Upgrading has thrown up the problems shown in the screenshot below. I have written to my hosting service about the https problem and a problem with the mysql database as I am running 5.5.30 but how do I resolve the three other checks below.
These are all advisory (orange). You can ignore them and carry on if you wish.
Thank you for your reply. So the only problem I have to solve is the mysql database upgrade and this has to be done through the hosting service, doesn't it? Also, I have version 3.5+: Is it worthwile updating to 3.5.4+ or waiting for 3.6.2+ if I have a problem with the mysql 3.6.
Moodle 3.5 is an LTS version (https://docs.moodle.org/dev/Releases#Moodle_3.5_.28LTS.29) so it's fine to work with it - updating it on regular basis! -, until you'll meet the requirements for 3.6+... unless you need specific features available only in Moodle 3.6.