There are lot of good articles on web with generic solutions to the problem of WordPress Error Establishing Database Connection, this post discuss about issue occurred during site migration to latest webhosting server. Wordpress Webserver Environment This issue is related to wordpress site migration to new cloud hosting server. The old webhosting server has following configuration The PHP version associated with wordpress site as PHP 5.3, WordPress version is 5.1.8 and MySQL version 5.1 which is also deprecated. The current website is running good from past few years, but with recent development it was required to upgrade. Since few plugins were not supported on PHP 5.3 and so we have decided to migrate the wordpress website to new cloud hosting