[1.1.x] raise exception when not recoverable | use exception subclass InputValidationError | use different handlers for exceptions | Implement upper lower case functions (#2586)

[deniszh]

Backport

This will backport the following commits from master to 1.1.x:

• raise exception when not recoverable
• use exception subclass InputValidationError
• use different handlers for exceptions
• Implement upper lower case functions (#2586)

Questions ?

Please refer to the Backport tool documentation