Upgrade failing

I am testing Discourse upgrade from version 3.0.3 to 3.0.4. After the upgrade Discourse is running, but after login to the system most of the pages/requests end up with 500 error.
In log files I see two different errors:

Job exception: PG::SyntaxError: ERROR: zero-length delimited identifier at or near """" LINE 1: ...1003061, "success" = TRUE WHERE "scheduler_stats"."" IS NULL
rack-mini-profiler-3.1.0/lib/patches/db/pg.rb:69:in `exec_params' rack-mini-profiler-3.1.0/lib/patches/db/pg.rb:69:in `exec_params' activerecord- `block (2 levels) in exec_no_cache' activesupport-


NoMethodError (undefined method `keys' for nil:NilClass) (eval):76:in `_fast_attributes' app/controllers/application_controller.rb:650:in `preload_current_user_data' app/controllers/application_contro
plugins/chat/lib/chat/channel_fetcher.rb:164:in `preload_custom_fields_for'
plugins/chat/lib/chat/channel_fetcher.rb:159:in `secured_public_channels'
plugins/chat/lib/chat/channel_fetcher.rb:9:in `structured'
plugins/chat/plugin.rb:239:in `block (2 levels) in activate!'
(eval):76:in `_fast_attributes'

When I downgrade system back to 3.0.3 everything works fine.

We are not using many plugins, but I also did one attempt with all plugins disabled. Same result.

Thanks in advance for any help.

3.2 stable is imminent. I would not bother with upgrading until that’s announced.

3.0.x is unlikely to be supported by many plugins and theme components.

Sorry, my mistake there. Upgrade I have troubles with is from 3.1.3 to 3.1.4. Motivation is to address CVEs fixed in 3.1.4.