Hi Steve,

Looking at the error I assume that it has been produced by the block of code which tries to upgrade the Nop Customer Reminders plugin. It appears that somehow the [Store] table could not be found. This table is generated by the nopCommerce upgrade script from 2.8 to 3.0 or when on a clean install it is installed by nopCommerce.
Can you please double check whether the [Store] table is present in your database on which you get the [SqlException (0x80131904): Invalid object name 'dbo.Store'.] exception.

The upgrade script should be run only when upgrading from version 2.8 to 3.0. In the second case you have described, when you have a clean install of nopCommerce 3.0 version, you do not need to run the upgrade script, but just install the plugins for version 3.0.

Looking forward to your reply.