similar to bug #67031 If attempting to allocate a partition of greater size than available space, if the "Force to be a primary partition" option is checked, then instead of the pop-up error dialog saying anything about space (see 67031), the error is "Could not allocate partitions as primary partitions" which is misleading since the partitions could not be allocated at all, primary or not. Simply unchecking the force and the error goes back to "Could not allocate partitions", as in 67031, still nothing about size issues
Similarly, not going to do this at the moment.