In configuration of "Control: Reason for movement" T-code OMBS , If reason for movement field value is "Entry in this field is required" then system not allow to you proceed furtherwithout entering proper reason in reason filed.*********************************If entry is mandatory in reason filed then enter below mentioned any suitable reason as per your requirement.And system is allow to proceed further.Examples-Poor quality ,Not identify-able,Certificate Missing,Certificate Incorrect,Spoiled,Incomplete,Damaged,Not matching spec.,Over Delivery,Late delivery and Other reasons.If you do not want reason while goods movement or you want it optional then in config. you have do some changes for require specific movement type.Steps-Go to T-code OMBS - Reason for movement, click on Control Reason button, Select specific movement type for which require entry is suppose to be optional or suppress and make reason filed - ' ' Entry in this filed is optional or'-' Filed is suppressed.After this setting while goods movement for specific movement type system does not ask reason for this particular movement type.