Okay, I upgrade to 1.4.2 successfully. And I noticed the same issue when trying to run the script with:
sh scriptname.sh, so I tried simply running with ./scriptname.sh. Which appeared to work, but then a different problem.
root@srv01:/usr/local/hestia/install/upgrade/manual# ./migrate_phpmyadmin.sh
For deleting PHPmyAdmin you will need confirm the removal with root password. Password can be found in /usr/local/hestia/conf/mysql.conf
Would you like to continue? [y/n]y
[ * ] Make backup old config files
[ * ] Remove PHPmyAdmin via ATP
phpmyadmin set on hold.
[ * ] Delete possible trail
[ * ] Create new folders
[ * ] Installing phpMyAdmin version v5.1.0...
tar (child): phpMyAdmin-5.1.0-all-languages.tar.gz: Cannot open: No such file or directory
tar (child): Error is not recoverable: exiting now
tar: Child returned status 2
tar: Error is not recoverable: exiting now
cp: cannot stat 'phpMyAdmin-5.1.0-all-languages/*': No such file or directory
sed: can't read /usr/share/phpmyadmin/libraries/vendor_config.php: No such file or directory
sed: can't read /usr/share/phpmyadmin/libraries/vendor_config.php: No such file or directory
[ * ] Createing localhost config
[ * ] Drop database could throw a error if successfull removal was preformed
[ * ] Create new user
[ * ] Create new database
root@srv01:/usr/local/hestia/install/upgrade/manual#
So it appears this is not working.
Also, attempting to access phpmydmin from the HestiaCP link results in this:

