Mastery changing makes a unexpected error once patch 5.4 came out

Well after 5.4 came out i have been having bugs when switching mastery pages saying in a big box "Unexpected Platform Error" with a Click ok button and nothing else happening.

As well on each mastery page if i edit it it puts a number beside the page ( so if its page 14 a (14) appears beside the page name) changing the name after that or trying to delete the number causes the unexpected error just like above