The error message in case the pseudonym provided does not match the requirements placed on it is:
Invalid pseudonym. It should be between 5 and 20 characters long and can only contain letters (A-Z, a-z), numbers (0-9), underscores (_), dots (.), hyphens (-) and spaces ( ).
Desired state
The error message should remind that diacritcal signs are forbidden.
Current state
The error message in case the pseudonym provided does not match the requirements placed on it is:
Invalid pseudonym. It should be between 5 and 20 characters long and can only contain letters (A-Z, a-z), numbers (0-9), underscores (_), dots (.), hyphens (-) and spaces ( ).
Desired state
The error message should remind that diacritcal signs are forbidden.