While login to your Joomla backend panel you might recieve below error:

Warning: Parameter 1 to JHTMLGrid::access() expected to be a reference, value given in /home/user/public_html/libraries/joomla/html/html.php on line 87

So to solve the issue just follow below steps:

1] Login to your server via SSH edit the above mentioned file by

vi /home/user/public_html/libraries/joomla/html/html.php

2] Once edited go to line 87,you will see below lines:

$args = func_get_args();
array_shift( $args );

Change the above lines to:

$temp = func_get_args();
array_shift( $temp );
$args = array();
foreach ($temp as $k => $v) {
$args[] = &$temp[$k];

3] Save the file and refresh the admin page URL Voila!! error gone...

See how easy it is!!