On 2nd page of Deploy Docker Image wizard is page containing environment variable. Dialog to create a new environment variable has a validation message but it is not correct, or at least validation message content does not fit reality. See following screenshots:

First one is when entered invalid environment variable name. Notice message contains info about invalid value, not name, although it is name what is not valid.

Second screeshoot displays so-called invalid value (regarding to validation message in first screenshot), but there is no validation error.