There are a few things going on here.
The error message initially indicates a permission problem with your hosting. You should contact your host’s support team about this. If you have control over this yourself, check how the permissions for the directories are set. Here is a general article on this topic: https://developer.ww.wp.xz.cn/advanced-administration/server/file-permissions/
“Feature Image” is a feature that is only available for posts by default. It can also be deactivated by plugins and themes. However, it can also be activated for other post types (such as pages). The approach you took to rule out plugins as the cause by deactivating them is the right one. Once you have resolved the permission issue with the theme, you may also be able to rule out the theme as the cause. Without plugins and with a standard theme, Feature Image must be available for posts.
i also tried editing the function.php file of my theme… (twenty twenty one)
FYI, it’s ill advised to alter any file of any theme that’s subject to periodic updates. If you want to temporarily test some custom code, that’s OK, but for a more permanent solution you should either create a child theme or bespoke plugin.
The featured image block in Elementor is a Pro only feature, but we can still manipulate featured images from the default block editor before entering Elementor.
It’s not clear why you’re getting an “Installation failed” error if you’re merely updating. If we try to install an existing theme, its directory cannot be created because it already exists. In order to simply update, there’s no reason to create a directory for the theme. Be aware that actual updating will likely remove any custom code you’ve added to functions.php, hence the reason for using a child theme or bespoke plugin.
