升级 v3.5.2 -\u003e v3.6.0.beta2 后数据库访问问题

Did you follow these instructions? (It doesn’t seem like it?)

It’s a pretty good bet, but make sure that you’ve got stuff like in the multisite install topic.

If your sites are working now then I too would encourage you to do a clean multisite install and backup/restore the databases over. You can copy all the other stuff as described in Move a Discourse site to another VPS with rsync