Editing a Date & Time field inside my quick edit grid will raise the following error :- “Invalid data has been used to update the list item. The field you are trying to update may be read only.”

I have created a custom content type based on the built-in "Event" content type. which have two columns "Start Time" and "End Time" of type Date and Time. now i can add a new item using the quick edit grid , for example i can specify the start time to be 15/03/YYYY 20:00 and end time to be 15/03/YYYY 21:00 , and the item will be saved correctly.

but the problem i am facing if i try editing the item using the quick edit grid , and i modify the end time to be 15/03/YYYY 22:00 instead of 21:00 , where i will get the following error:-

    Invalid data has been used to update the list item. The field you are trying to update may be read only.

but if i edit the item using the edit form , i will not receive any error ? so can anyone advice on this please? why i am unable to edit the end time using the quick edit grid ?? keeping in mind that i can i modify the title, agenda and other fields using the quick edit without any problem ??