Hi @prdv,
Personally I agree and I wouldn’t mind if every post on this forum was made in English. (As I would not have to repeat myself as often). But as Matomo is used by a lot of people who don’t know English or (more likely) don’t feel too comfortable with their proficiency, also helping people in German means that more people can enjoy using Matomo.
So as this is a post that will probably be found by quite a few users, a quick English summary:
Those SQLSTATE errors come directly from MySQL and depend a lot on how your setup between MySQL and PHP works. In this case it seems like the shared host is limiting the simulaneous connections quite strongly, but switching the default MySQL adapter from PDO to MYSQLI (which normally doesn’t work as well for some users) did the trick here to make everything work again.