Note 5 at Jn. 20:17: Just one week after this (Jn. 20:19 with 20:26), Jesus told Thomas to touch Him and believe that He was alive from the dead (Jn. 20:26-27). Therefore, this instance where Jesus told Mary not to touch Him could be an admonition not to cling to Him (as some translations have it) because there would be other times that He would see her before His ascension.

Some scholars also speculate that after this visit with Mary, Jesus ascended to His Father and then returned and spoke to Thomas. If this is the case, we can only guess as to what He had to do in Heaven that would have caused Him to forbid Mary Magdalene from touching Him. Some think that Jesus ascended to His Father that very day and sprinkled His blood on the mercy seat in heaven (Lev. 16:14).

However, in Jesus' next appearance to the other women (Mt. 28:9), they held Him by the feet. This means that Jesus would have had to ascend to His Father and return in just a couple of minutes or else His command to Mary Magdalene to not touch Him was just referring to not clinging to Him.