[Technical Task] Recheck server-side validation error messages in codebase

[Michael-Kolpakov]

Brief overview

After the big wave of PR merges, your completed work in the ticket #308 is a bit outdated and you need to review a new codebase to update it to your one style.

Expected result

Current codebase using Resources to print server-side validation errors.

Attachments

An example of one of the PRs that use hardcoded messages:
#1668

The way how you did it in your PR: