I am going to recap all the commands used so far, plus adding a new one for this permission error.
chmod g+w /opt/bitnami/apps/prestashop/htdocs/
chmod g+w /opt/bitnami/apps/prestashop/htdocs/administration/autoupgrade
chmod g+w /opt/bitnami/apps/prestashop/htdocs/administration/autoupgrade/backup
chmod g+w /opt/bitnami/apps/prestashop/htdocs/vendor/composer/include_paths.php
However, the plugin is likely to ask for write permissions in the whole htdocs folder. It is not a good practice to grant such as permissions, but most of the upgrade plugins require this privilege in order to easy maintenance tasks.
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