If you are using the Taps Extension in your project, kindly download the Tabs Extension and use that one instead. in my situation, that was what gave me this error problem whiles uploading to the Store.
Note: Taps (with P) and Tabs (with B).
whiles it might look Tedious to re-code part of your blocks with the Tabs extension, i would suggest you do not delete the TAPS at first but instead, upload the TABS extension, drag it into your project and replace each part of the code that contains the TAPS with the TABS. After that is done, delete the TAPS extension from your project and also from the extension drawer(panel)