This problem usually occurs when you are trying to install a plugin or theme frfom the .zip file that you have downloaded.
Let’s be clear, what is the reason for this
This usually happens due to the extra files which are stored inside that zip folder that you are trying to install. The extra files can be a demo text, an extra child theme or any free zip with the theme or plugin.
How to solve this?
You just have to extract the .zip file which you have downloaded from our website and then you will find another installable .zip file inside that. Simply import that and install and the problem wil be solved.
Since this is not a problem, but many of people faces this due to being unaware of the technique to install the file.