Moved my site from folder to the root but no site

I have moved my site from a folder I was using to develop the site to the root to make it live and now I get a blank page. The site it going from C5.6 to C5.8. I have checked dispatcher file that looks ok. Any ideas please?

Check .htaccess (RewriteBase must be / in your case) and application/config/site.php (canonical urls, if you set them, must point to domain root).
Also, delete all files in application/files/cache.

Looking for errors in browser console might be a good idea also.

Later edit: check the PHP error log file and see if there is something related.

Deleting cached files worked thanks