Please use this thread going forward: Sims/Pets age up multiple times in a row | EA Forums - 4958279
My infant sim was ageing up to a toddler as it was the end of their life stage. However, birthdays queued up one after another and so he aged to toddler, then immediately aged to a child, then teen, then young adult, in the space of about a minute. When the birthday popped up on the left hand side I tried to cross it off, but no luck. My poor infant!
Move your Mods folder to the Desktop and delete localthumbcache.package. Then test the game in a new save.
If it works now check for updates to your Mods and CC. Add it back a little at a time while testing until you have found all that are broken.
One of my infant sims aged up to a toddler soon after starting the game and then aged to a child immediately after. There aren't issues with any other sims in my current save.
