I actually wanted to upgrade your extension to 1.2.1 but got an error message, so I went back to my original version.

and the error i get at setup:upgrade after upgrading your module to 1.2.1 is:

  Class Magento\Framework\Serialize\Serializer\Serialize does not exist


The issue is due to an incompatibility issue on Magento 2.1.x.

Please use the patch below to overwrite the files on your site and fix the issue.

- app/code/Bss/Simpledetailconfigurable/Helper/ModuleConfig.php ModuleConfig.php

- app/code/Bss/Simpledetailconfigurable/Model/Import/Preselect.php Preselect.php

Please let us know if you have any other issues.

We are always willing to support.