WordPress often installs easily, but if you encounter problems, there are things you can do to troubleshoot the installation. These common WordPress installation problems are some that you might run into.

Common WordPress Installation Problems
Error Message Common Cause Solution
Error Connecting to the Database The database name, username, password, or host was entered incorrectly. Revisit your MySQL database to obtain the database name, username, password, and host and then reenter that information.
Headers Already Sent Error Messages A syntax error occurred in the wp-config.php file. Open the wp-config.php file in a text editor. The first line should contain only this line: <?php. The last line should contain only this line: ?>. Make sure that those lines contain nothing else — not even white space. Save the file changes.
500: Internal Server Error Permissions on PHP files are set incorrectly. Try setting the permissions (chmod) on the PHP files to 666. If that change doesn't work, set them to 644. Each Web server has different settings for how it lets PHP execute on its servers.
404: Page Not Found The URL for the login page is incorrect. Double-check that the URL you’re using to get to the login page is the same as the location of your WordPress installation (such as http://yourdomain.com/wp-login.php).
403: Forbidden Access An index.html or index.htm file exists in the WordPress installation directory. WordPress is a PHP application, so the default home page is index.php. Look in the WordPress installation folder on your Web server. If an index.html or index.htm file is in there, delete it.