cp /usr/share/phpmyadmin/config.sample.inc.php /usr/share/phpmyadmin/config.inc.php
$cfg['blowfish_secret'] = 'KLS$vbc91Lkja$vc@opGbxA278EWopdc';//step 1: To generate new blowfish secret
simply hit this https://phpsolved.com/phpmyadmin-blowfish-secret-generator/?g=5d94be5065c70
or
openssl rand -base64 32
//step 2: rename cofig sample of phpmyadmin to config
cp /usr/share/phpmyadmin/config.sample.inc.php /usr/share/phpmyadmin/config.inc.php
//step 3: add the code generated in step 1
$cfg['blowfish_secret'] = 'your_pass_key_here_xkdfsdf@kfa#fsd@sdf';//first copy file from
cp /usr/share/phpmyadmin/config.sample.inc.php /usr/share/phpmyadmin/config.inc.php
//open the file
sudo nano /usr/share/phpmyadmin/config.inc.php
// then find $cfg['blowfish_secret'] = '';
//set a passkey
$cfg['blowfish_secret'] = 'your_pass_key_here_xkdfsdf@kfa#fsd@sdf';