To go wake up my toddler, been napping 2.5 hours now...

[Turneeps]

15 months old.
Normally naps 1.5 hours in morning and 1.5 hours in afternoon. Night is 7-6.30.
Last 3 nights she has cried loads going to bed at night when she usually is great at going to sleep.
Today she has not woken up from morning nap, and is still napping 2.5 hours just gone. Do I wake or is this the transition to one nap a day??

I hate waking a sleeping baby/toddler but how long a nap is too long???

Could be transition, but for me that happened when DS was refusing to go down for afternoon sleep rather than evening.

Maybe leave her for now and see if you can manage the rest of the day without another sleep? Or a short cat nap later only?

Good luck, this is a bit of a crap time.

I will say though, as soon as we dropped the second nap, DS extended his after lunch sleep to 2 hours (from 1.5) and started sleeping through the night.

Around that age my dd started been a madam going sleep at night and then napping for hours during day because she was so tired from night before. Now at 20 months she goes to bed at half 7 sleeps until about 7 half 7 then naps at 11 half 11 until about 1 half 1.

Sounds like transition. When DD started doing this I waited a month then started keeping her awake till after lunch. We had about 3 weeks of 11.30 lunches!

She woke up herself after 2h45m. Crying because hungry as missed normal 11.45-12 lunch!
I'll see if she can stay awake all afternoon.

Just an update,,,
Was yawning her head off by 2.30pm and crying by 3 so I put her to bed. She slept 1 hour then I woke her up.
Grumpy tired by 6pm and bed at 7(with 15 min of crying). Mega sleepy day! WTF!
I have no idea what is going on.

Sounds like she's fighting off an illness and needs to sleep as that's when the body heals.

It sounds to me like she might be getting sick. I'd let her sleep, she obviously needs it.