Internal Server Error 500 on GoDaddy when visiting /panel

I’m having an 500 error when visiting /panel url.
Instead all other pages works correctly. Any ideas?

Update 1: I’ve added Options -Multiviews & RewriteBase / to .htaccess without any success…

Update 2: Ok it’s very weird: initially I was using Kirby and Panel git submodules and now I tried to download Starterkit and placing Kirby & Panel folders manually to my project and it works… tomorrow I will compare these two.