The latest version of phpmyadmin does not create the config file after installation. There is an example config file available and an actual default config file deeper in the folder tree.
Note that the blowfish secret must be exactly 32 characters in length else it will not be applied.
Copy the example file to create the actual used file that overrides defaults. The directory shown below is just an example, therefore use the directory/path for your phpmyadmin installation that applies.
cp /usr/share/phpmyadmin/config.sample.inc.php /usr/share/phpmyadmin/config.inc.php
At the top of the file is the blowfish variable that needs to be set. Add 32 random characters to the variable’s value and then save the file.
$cfg['blowfish_secret'] = '[email protected]';
I did not read anyone mentioning the 32 character rule in this thread.
Perhaps that was the issue for the OP.