I didn't have it easy, but I learned something new, thanks Steve.
Qotd from 2016/08/31 was brilliant, because all the first three answers were right... 😉
The first error was, that the HireDate was not in the definition of the view NewEmployees.
If HireDate was added to the definition, an error occurred while converting date '20150230'.
After the repair to the '20150228' was finally the third error, which is interestingly specified:
"The attempted insert or update failed because the target view either specifies WITH CHECK OPTION
or spans a view that specifies WITH CHECK OPTION and one or more rows resulting from the operation
did not qualify under the CHECK OPTION constraint. The statement has been terminated."
A good explanation is at https://www.sqlservercentral.com/articles/Stairway+Series/107120/