I created a website using Wordpress on a local server and the migrated it to an online server both manually and using the plugin Duplicator. All went fine and I have the same configuration of the localhost site, with all the pages set correctly. My problem is this: when I open my Website I continue to see "Page not found" and 404 errors even it the page exists and I can see it in the Wordpress page settings. In addition when I enter my domain a "/wp/" is added at the end, so it's like "www.mydomain.com/wp/" and I get the "Page not found" errors. How can I resolve this issue? Thank you so much in advance!
WordPress stores on the options table two urls for the site: siteurl and home. They should be the first two entries in the options table. Make sure that after migrating those two options match with your new domain. Duplicator should have taken care of it but just check to make sure.
First, try what @freejack said. Replace the siteurl and home from wp-options table in the database. Then delete the.HTACCESS file from the root folder & try to run the site. Once the site runs, refresh the permalink and perform a search-replace on the database.