This is a common issue that can be occurred during to upload themes. If you have the same errors, "The package could not be installed. The theme is missing the style.css stylesheet." "If it is coming, then it can be easily resolved.
As you know that written in the error that the “theme is missing the style.css stylesheet. Your path is wrong from where you are uploading the theme, you need to upload a folder or zip file with content from your main theme zip file.
Let's take an example –
Suppose that you download a hotel website theme that downloads into zip file, then you upload the same zip file to the direct but you got the error “The theme is missing the style.css stylesheet "After that you will get that zip file Unzip it and inside it you will get a zip file or you will find a folder in which you will have content and you have to upload it, if you install a zip and another zip file inside it Then met the same name you just upload If found folder same name you need to convert in ZIP file and upload it ..
Let's take with an example .
Enjoy your theme has been successfully installed.