ERROR 1452: Cannot add or update a child row: a foreign key constraint fails (`development`.`#sql-1228_15f`, CONSTRAINT `FK_ORDERS_ID` FOREIGN KEY (`ORDER_ID`) REFERENCES `orders` (`ORDER_ID`)) code example

Example: integrity constraint violation: 1452 cannot add or update a child row: a foreign key constraint fails

It just simply means that the value for column project_id on table comments you are inserting doesn't exist on table projects. Bear in mind that the values of column project_id on table comments is dependent on the values of ID on table Projects.

The value 50dc845a-83e4-4db3-8705-5432ae7aaee3 you are inserting for column project_id does not exist on table projects.