This might be late but I faced the same issue. Make sure that you are not missing the bootconfig.json file in your project directory. If the file is missing add the file to your project and rebuild it. Hope this helps.
Sorry for the late answer , I believe the below step might help you.
you can manually add the Salesforce SDK to your project
create a new folder called mobileSDK
and add in the iOS [sdk] and Android [SDK] from salesforce
preferred way is just add a new file for each ios and android
For android create a new file in project root call it "...