Upon wanting to install dutch language file i get the following error message after hitting the Commit button:

Warning: copy(/var/www/vhosts/anansie.nl/httpdocs/crm/./manifest.php) [function.copy]: failed to open stream: Permission denied in /var/www/vhosts/anansie.nl/httpdocs/crm/modules/Administration/UpgradeWizard_commit.php on line 208
Could not copy file /var/www/vhosts/anansie.nl/httpdocs/crm/cache/upload/upgrades/temp/PzQphH/./manifest.php to /var/www/vhosts/anansie.nl/httpdocs/crm/./manifest.php

in this thread the person had the same issue. However, his solution seems not perfect to me. I would need to upload all files via ftp. This would take to long, and i am afraid that i will get problems in the future if i might want to install other modules.

any suggestions (please be specific, as server issues are not my expertise)