translation of field labels leads to an error

[rallek]

Profile 3.0.0 (shipped with zk 1.5.0)

I change the translation of the former called field _UREALNAME

after saving I do get the following:

Oops! An Error Occurred
The server returned a "500 Internal Server Error".
Something is broken. Please let us know what you were doing when this error occurred. We will fix it as soon as possible. Sorry for any inconvenience caused.

The options "pattern" must be set for constraint Symfony\Component\Validator\Constraints\Regex