Can a motion to withdraw a plea of guilty be appealed without a certificate of probable cause?

The alleged failure to warn defendant of the effect of a plea of guilty on his right of appeal and the refusal to grant a continuance, however, are clearly matters occurring before the entry of the plea and affecting the validity of the plea. We have previously rejected the proposition that denial of a motion to withdraw a plea of guilty may always be appealed without a certificate of probable cause because it always occurs after the entry of the plea. The determinative factor is when the claims upon which the motion was based arose and not when the motion to withdraw was denied. (People v. Ribero (1971) 4 Cal.3d 55, 63--64, 92 Cal.Rptr. 692, 480 P.2d 308.) Because no certificate of probable cause was obtained, these two issues may not be raised on this appeal.