This morning I have been trying to copy my existing PW site to a new web root, as well as up one level in hierarchy (i.e. the old site was "fypnew/processwire" but the new site should be just "fyp").
I've copied the server files to the new location, edited the root level .htaccess file to point to /fyp/ as the new RewriteBase, and confirmed that the PW database user can still access the PW database (I am not planning on migrating the database location).
I am getting the 500 error when loading the new location in my web browser. I am pretty sure the web server is reading the .htaccess file, and that it has the right permissions. I suspect I am missing some other piece of the puzzle? I am not sure how to debug from here, or what to do next, although I am looking at the PW Profile Exporter module.