Fatal Error: undefined function mysql_connect()

Though, running php -m at the command line would say, that mysql extension is ready and loaded. And phpinfo() would show it as not loaded. After checking apache’s logs/error.txt i found that php is unable to load quite a few of the php.ini enabled extensions.

PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_curl.dll’ – The specified procedure could not be found.\r\n in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_mcrypt.dll’ – The specified module could not be found.\r\n in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_mhash.dll’ – The specified procedure could not be found.\r\n in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_mysql.dll’ – The specified procedure could not be found.\r\n in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_mysqli.dll’ – The specified procedure could not be found.\r\n in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_soap.dll’ – The specified procedure could not be found.\r\n in Unknown on line 0
PHP Warning: PHP Startup: Unable to load dynamic library ‘c:\\php\\ext\\php_xmlrpc.dll’ – The specified procedure could not be found.\r\n in Unknown on line 0

I started googling on the matter to find out what went wrong with the upgrade. After reading a PHP bug report I realized that it might have something to do with my windows/system32 dlls. Then I found php5ts.dll in the windows/system32 directory.

It became clear to me, that PHP CLI version was using the the DLL’s from the php directory and PHP as an Apache module was loading them from the windows\system32 directory. I deleted all of the DLLs that are in the PHP directory from the windows/system32 directory and added PHP directory path to PATH environment variable and everything seems to work fine now.

My personal advice is not to put any of PHP DLL’s in the windows/system32 directory. You may really forget you have them there and become confused why things have started acting strangely.