Hi Vij,
The FM GUID_CREATE becomes absolute in new versions, as it is already used in standard fm's, it will work fine and it wont give any error. You can just reset to original.
Instead you can use class CL_SYSTEM_UUID and below methods to create GUID in Future.
IF_SYSTEM_UUID_STATIC~CREATE_UUID_X16
IF_SYSTEM_UUID_STATIC~CREATE_UUID_C22
IF_SYSTEM_UUID_STATIC~CREATE_UUID_C26
IF_SYSTEM_UUID_STATIC~CREATE_UUID_C32
If you want to change the existing standard code,you need access key for that object.
Regards,
Varma