Upgrade 2.0.15 - 2.1.0 rewrite broken

I just extended my updates .

so so i try to do the

Upgrade 2.0.15 - 2.1.0

when i get to 2.1.0

my links no longer work

SEO links take me to 404 not found .

any ideas ?

I was testing your store before you closed it and SEO links seemed to be working fine

they where only working cause i reverted .