Question: mat-datepicker is not a known element?
Answer: Error: 'mat-form-field' is not a known element If 'mat-form-field' is an Angular component, then verify that it is part of this module. 2. If 'mat-form-field' is a Web Component then add 'CUSTOM_ELEMENTS_SCHEMA' to the '@NgModule. schemas' of this component to suppress this message.